Fluid injection system

Abstract

This invention discloses a plunger for use with a syringe, comprising a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal end and the distal end. The plunger further includes at least one retaining member associated with the plunger body and extending from the proximal end of the plunger body. The at least one retaining member has a second end connected to a first end of the plunger body, proximal to the first end and radially and resiliently deflectable relative to the first end, and at least one latch on the second end. This invention also discloses a fluid injector system comprising a piston having a plunger engagement mechanism configured to interact with the at least one retaining element of the plunger to releasably engage the plunger to reciprocate the plunger within a barrel of a syringe.

Description

Technical Field

[0001] The present invention is generally related to a system comprising a preloaded syringe and / or pressure sheath for use with a fluid injector, and further relates to a connection interface for securing a syringe plunger to a piston of the fluid injector and a method for engaging and disengaging the syringe plunger from the piston of the fluid injector. Prior Technology

[0002] In many medical diagnostic and treatment procedures, a practicing physician injects one or more medical fluids into a patient. Mass-operated syringes and fluid injectors have been developed for the pressurized injection of fluids such as a contrast fluid (often simply referred to as "contrast"), an irrigation solution (such as saline or Ringer lactate), and other medical fluids in contrast-enhanced imaging procedures such as angiography, computed tomography (CT), ultrasound, magnetic resonance imaging (MRI), positron emission tomography (PET), and other imaging procedures. Generally, these fluid injectors are designed to deliver a preset volume of one or more fluids at a preset flow rate.

[0003] Typically, a fluid injector has at least one drive member, such as a piston, connected to a syringe via, for example, an engagement feature on a plunger or a proximal wall of a syringe. The syringe may include a rigid barrel and a syringe plunger slidably disposed within the barrel. The at least one drive member is configured to drive the plunger in a proximal and / or distal direction relative to a longitudinal axis of the barrel to draw fluid into or deliver fluid from the syringe barrel.

[0004] Various connection interfaces have been developed to facilitate engagement between a syringe plunger and a piston of a fluid injector. In some embodiments, a syringe having a retaining feature is inserted into a syringe port on a fluid injector by aligning the syringe with a corresponding locking feature disposed on the fluid injector. This alignment also aligns the plunger in the syringe with the piston on the fluid injector, such that the piston can engage the plunger and reciprocate the plunger through the syringe barrel to draw fluid into or deliver fluid from and to the syringe barrel. In other embodiments, after initial engagement with the plunger, the piston is rotated in a clockwise or counterclockwise direction until the piston engages a latch on the plunger. In a further embodiment, the piston has a radially extendable pin that engages a lip on the plunger.

[0005] Many existing connection interfaces require a complex piston head and various sensor elements and active engagement mechanisms. This technology requires an improved connection interface that allows for simpler and easier engagement and disengagement of the syringe plunger and the fluid injector piston. This technology further requires reducing or eliminating the need for the operator to rotate the syringe and fluid injector for alignment before engaging the syringe plunger and the fluid injector piston. Although various syringe connection interfaces and methods are known in the medical field, there is a need for continuous improvement of the connection interface between the syringe plunger and the fluid injector piston, and the methods for engaging and disengaging the syringe plunger and the fluid injector piston. Summary of the Invention

[0006] This technology needs to overcome one of the drawbacks of prior art: an improved connection interface between a syringe plunger and a piston of a fluid injector. Additionally, an improved method is needed for engaging and disengaging a syringe plunger from a piston of a fluid injector to allow for the immediate loading of a syringe into or removal of a syringe from a fluid injector.

[0007] According to some embodiments, a plunger for use with a syringe may include: a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal end and the distal end; and at least one retaining member associated with the plunger body and extending from the proximal end of the plunger body, the at least one retaining member including: a first end connected to the plunger body; a second end proximal to the first end and radially and resiliently deflectable relative to the first end; and at least one latch located on the second end, wherein the at least one retaining member may have a configuration to engage a plunger engagement sleeve of a plunger engagement mechanism to a piston of a fluid injector system when the plunger is in a locked state with the piston. An outer surface, wherein the at least one retaining member may have an inner surface configured to engage one of the plunger engagement posts of the plunger engagement mechanism when the plunger is in the locked state with the piston, wherein the at least one lever may be configured to engage a locking feature on one of the plunger engagement sleeves and the plunger engagement posts to prevent axial movement of the plunger relative to the piston when the plunger is in the locked state with the piston, and wherein the at least one lever may be configured to radially deflect the second end of the at least one retaining member after axial movement of the piston relative to the plunger in an unlocked state with respect to the piston, due to engagement of the at least one lever with the locking feature on one of the plunger engagement sleeves and the plunger engagement posts.

[0008] According to some embodiments, the at least one retaining member may comprise a plurality of retaining members spaced apart around the central longitudinal axis. The plurality of retaining members may be equally spaced around the central longitudinal axis. The at least one retaining member may extend proximally in a direction parallel to the central longitudinal axis or in a direction at an angle relative to the central longitudinal axis. The at least one retaining member may be linearly or curvilinearly connected between the first end and the second end. The plunger may be configured to engage the plunger engagement mechanism regardless of the angular orientation of the plunger relative to the piston of the fluid injector.

[0009] According to some embodiments, the at least one lever may have a first surface at the proximal end of one of the at least one lever configured to engage one of the plunger engagement sleeve and one of the plunger engagement pins during plunger engagement with the piston, and a second surface at the distal end of one of the at least one lever configured to engage one of the plunger engagement sleeve and one of the plunger engagement pins during plunger disengagement from the piston, at the proximal end of one of the at least one lever.

[0010] According to some embodiments, the at least one lever may protrude radially inward from the inner surface of the at least one retaining member in a direction toward the central longitudinal axis or radially outward from the outer surface of the at least one retaining member in a direction away from the central longitudinal axis. The at least one lever may define a locking groove for receiving at least a portion of the plunger engagement mechanism when the plunger is connected to the piston. The at least one lever may protrude radially inward from the inner surface of the at least one retaining member in a direction toward the central longitudinal axis, and the at least one lever may be configured to be received within a locking feature when the plunger is in the locked state with the piston, the locking feature being shaped as a locking groove protruding radially inward from the outer surface of the plunger engagement post.

[0011] According to some embodiments, the plunger body may have a conical portion at the distal end and a cylindrical portion at the proximal end. The at least one retaining member may protrude from the proximal end of one inner surface of the conical portion. A plurality of release lugs may protrude radially inward from or from the proximal end of the inner surface of one inner surface of the cylindrical portion, each of the plurality of release lugs being configured to interact with the plunger engagement sleeve to release the plunger from the piston after rotation of the plunger about the central longitudinal axis. The proximal end of each of the plurality of release lugs may have a pointed guide surface.

[0012] According to some embodiments, a plunger cap may cover at least a portion of a distal surface of the plunger body and may include a seal disposed around at least a portion of the circumferential sidewall of the plunger body.

[0013] According to some embodiments, the plunger can be configured to be slidably positioned within a barrel of a syringe. The plunger can be configured to reciprocate within the barrel of the syringe.

[0014] According to some embodiments, a fluid injector system may include: at least one reciprocating piston having a piston head; and a plunger engagement mechanism associated with the piston head and configured to engage a plunger connected to a syringe of the fluid injector system to reciprocately drive the plunger in the syringe due to movement of the at least one piston. The plunger engagement mechanism may include: a plunger engagement sleeve having a hollow body; a plunger engagement post received within the hollow body of the plunger engagement sleeve; and an actuator operatively connected to the plunger engagement sleeve and the plunger engagement post. One of the plunger engagement sleeves and plunger engagement posts is configured to move between an engaged position and a disengaged position, wherein in the engaged position, the plunger engagement post is positioned within the hollow body of the plunger engagement sleeve to capture at least one resiliently flexible retaining member associated with the plunger in a receiving space between the plunger engagement collar and the plunger engagement post, and wherein in the disengaged position, the plunger engagement post is at least partially positioned outside the hollow body of the plunger engagement sleeve to allow flexible insertion or removal of the at least one resiliently flexible retaining member of the plunger from the receiving space.

[0015] According to some embodiments, the actuator may be a rotary electric motor, a linear electric motor, a linear actuator, or a solenoid. According to some embodiments, the actuator is manually operable. The actuator may have an engaged state for moving one of the plunger engagement sleeve and the plunger engagement pin to the engaged position and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement pin to the disengaged position. The actuator may automatically move to the disengaged state during actuator de-energization. The actuator may be in the engaged state only during proximal movement of the at least one piston. At least one biasing element may be provided for moving the actuator from the engaged state to the disengaged state.

[0016] According to some embodiments, the rotational movement of the actuator can move one of the plunger engagement sleeve and the plunger engagement pin proximally or distally in a linear direction. According to some embodiments, the linear movement of the actuator can move one of the plunger engagement sleeve and the plunger engagement pin proximally or distally in a linear direction. The actuator is operatively connected to a controller configured to control the actuation of the actuator.

[0017] According to some embodiments, one of the plunger engagement sleeve and the plunger engagement pin can move linearly or rotationally relative to the piston, while the other of the plunger engagement sleeve and the plunger engagement pin can be stationary relative to the piston. The plunger engagement pin and the plunger engagement ring can move linearly or rotationally relative to the piston.

[0018] According to some embodiments, at least one sensor can be configured to detect a position of at least one of the plunger engagement collar and the plunger engagement post between the engaged position and the disengaged position. A plunger detection sensor can be configured to detect the presence of the at least one retaining member of the plunger in one of the receiving spaces between the plunger engagement collar and the plunger engagement post.

[0019] According to some embodiments, the hollow body of the plunger engagement sleeve may have an opening having a stepped inner diameter that decreases in a direction from a distal end of one of the plunger engagement sleeves to a proximal end of one of the plunger engagement sleeves. The plunger engagement post may include a locking groove projecting radially inward from an outer surface of one of the plunger engagement posts, and the locking groove may be configured to receive at least one latch on the at least one retaining member of the plunger. A distal edge of the locking groove may be configured to flexibly deflect the at least one retaining member of the plunger during axial movement of the plunger relative to the piston, so as to disengage the at least one latch of the at least one retaining member from the locking groove when one of the plunger engagement sleeves and the plunger engagement post is movable to the disengaged position. The plunger engagement post may have a body having a stepped outer diameter that decreases in a direction from a distal end of one of the plunger engagement posts to a proximal end of one of the plunger engagement posts.

[0020] According to some embodiments, the plunger engagement sleeve may include a locking feature that projects radially inward from one inner surface of the plunger engagement sleeve. The locking feature may be configured to engage at least one latch on at least one retaining member of the plunger when one of the plunger engagement sleeve and the plunger engagement pin is movable to the engaged position. The locking feature may be configured to flexibly deflect the at least one retaining member of the plunger during axial movement of the plunger relative to the piston, so that when one of the plunger engagement sleeve and the plunger engagement pin is movable to the disengaged position, the at least one latch on the at least one retaining member disengages from the locking feature.

[0021] According to some embodiments, the fluid injector system may further include the syringe having: a barrel having a proximal end, a distal end having a discharge nozzle, and a barrel sidewall extending between the proximal end and the distal end; and a plunger slidably disposed within the barrel and reciprocating between the proximal end and the distal end.

[0022] According to some embodiments, the plunger may include: a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal end and the distal end; and the at least one retaining member associated with the plunger body and extending from the proximal end of the plunger body.

[0023] According to some embodiments, the at least one retaining member may include: a first end connected to the plunger body; a second end adjacent to the first end and radially and resiliently deflectable relative to the first end; and at least one lever located on the second end, wherein the at least one retaining member may have an outer surface configured to engage a plunger engagement sleeve when the plunger is engageable with the piston, wherein the at least one retaining member may have an inner surface configured to engage a plunger engagement post when the plunger is engageable with the piston, wherein the at least one lever may be configured to engage a locking feature on either the plunger engagement sleeve or the plunger engagement post when the plunger is engageable with the piston to prevent axial movement of the plunger relative to the piston, and wherein the at least one lever may be configured to radially deflect the second end of the at least one retaining member after axial movement of the piston relative to the plunger in a disengaged state, due to contact between the at least one lever and the locking feature.

[0024] According to some embodiments, the plunger can be configured to engage the plunger engagement mechanism regardless of the angular orientation of the plunger relative to the piston of the fluid injector. The at least one latch can project radially inward from the inner surface of the at least one retaining member in one direction toward the central longitudinal axis. The at least one latch can be configured to be received within a locking feature when the plunger is in the locked state with the piston, the locking feature being shaped as a locking groove projecting radially inward from one outer surface of the plunger engagement post.

[0025] According to some embodiments, the at least one lever may protrude radially inward from the inner surface of the at least one retaining member in a direction toward the central longitudinal axis. According to some embodiments, the at least one lever may protrude radially outward from the outer surface of the at least one retaining member in a direction away from the central longitudinal axis.

[0026] According to some embodiments, the plunger body may have a conical portion at the distal end and a cylindrical portion at the proximal end. At least one retaining member may protrude from the proximal end of one inner surface of the conical portion. A plurality of release lugs may protrude radially inward from the inner surface of one inner surface of the cylindrical portion, each of the plurality of release lugs being configured to interact with the plunger engagement sleeve to release the plunger from the piston after rotation of the plunger about the central longitudinal axis. The proximal end of each of the plurality of release lugs may have a pointed guide surface.

[0027] According to some embodiments, a fluid injector system may include: at least one reciprocating piston having a piston head; and a plunger engagement mechanism associated with the piston head and configured to engage a plunger connected to a syringe of the fluid injector system to reciprocately drive the plunger in the syringe due to movement of the at least one piston, the plunger engagement mechanism including: a plunger engagement sleeve having a hollow body including a longitudinal axis; and a plunger engagement post received in the hollow body of the plunger engagement sleeve and axially movable relative to the plunger engagement sleeve between an engaged position and a disengaged position, wherein the plunger engagement sleeve is rotatable about the longitudinal axis between a first position and a second position, and wherein the plunger engagement post is axially movable along the longitudinal axis from the engaged position to the disengaged position via rotation of the plunger engagement sleeve.

[0028] According to some embodiments, the plunger engagement pin is axially movable from a proximal end of one piston toward a distal end of one piston. The plunger release sleeve may include a plurality of plunger release teeth projecting radially outward from an outer surface of one of the hollow bodies. The plurality of plunger release teeth may be configured to engage a plurality of release lugs on the plunger, such that rotation of the plunger about a longitudinal axis causes rotation of the plunger engagement sleeve about the longitudinal axis.

[0029] According to some embodiments, a plunger release sleeve may surround at least a portion of the plunger engagement sleeve, wherein the plunger release sleeve may be configured to rotate about the longitudinal axis as the plunger engagement sleeve rotates. The plunger release sleeve may include an opening having an inclined surface that is angled relative to the longitudinal axis in a direction from a distal end of the plunger release sleeve toward a proximal end of the plunger release sleeve.

[0030] According to some embodiments, the plunger engagement post may have a guide pin extending in a direction perpendicular to the longitudinal axis, wherein the guide pin may be received within the opening of the plunger release sleeve. Rotation of the plunger engagement sleeve may cause a corresponding rotation of one of the plunger release sleeves. The guide pin may be guided along the inclined surface from a proximal end of the inclined surface toward a distal end, thereby moving the plunger engagement post from the engaged position to the disengaged position.

[0031] According to some embodiments, a biasing member is operatively connected to the plunger engagement sleeve and the plunger engagement post. The biasing member can be configured to bias the plunger engagement sleeve to the first position.

[0032] According to some embodiments, an actuator is operatively connected to the plunger engagement post and configured to move the plunger engagement post between an engaged position and a disengaged position. In the engaged position, the plunger engagement post is positioned within the hollow body of the plunger engagement sleeve and configured to capture at least one resilient flexible retaining member associated with the plunger in a receiving space between the plunger engagement collar and the plunger engagement post. In the disengaged position, the plunger engagement post is at least partially positioned outside the hollow body of the plunger engagement sleeve to allow flexible insertion or removal of the at least one resilient flexible retaining member of the plunger from the receiving space.

[0033] According to some embodiments, the actuator may be a rotary electric motor, a linear electric motor, a linear actuator, or a solenoid. According to some embodiments, the actuator can be manually operated. The actuator may have an engaged state for moving one of the plunger engagement sleeve and the plunger engagement pin to the engaged position and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement pin to the disengaged position. The actuator may automatically move to the disengaged state during actuator de-energization. The actuator may be in the engaged state only during proximal movement of the at least one piston.

[0034] According to some embodiments, at least one biasing element is used to move the actuator from the engaged state to the disengaged state. Rotation or linear movement of the actuator causes one of the plunger engagement sleeve and the plunger engagement pin to move proximal or distal in a linear direction. The actuator is operatively connected to a controller configured to control the actuation of the actuator.

[0035] According to some embodiments, at least one sensor can be configured to detect a position of at least one of the plunger engagement collar and the plunger engagement post between the engaged position and the disengaged position. A plunger detection sensor can be configured to detect the presence of the at least one retaining member of the plunger in one of the receiving spaces between the plunger engagement collar and the plunger engagement post.

[0036] According to some embodiments, the hollow body of the plunger engagement sleeve may have an opening having a stepped inner diameter that decreases in a direction from a distal end of one of the plunger engagement sleeves to a proximal end of one of the plunger engagement sleeves. The plunger engagement post may include a locking groove projecting radially inward from an outer surface of one of the plunger engagement posts, wherein the locking groove may be configured to receive at least one latch on at least one retaining member of the plunger. A distal edge of the locking groove may be configured to flexibly deflect the at least one retaining member of the plunger during axial movement of the plunger relative to the piston, so as to disengage the at least one latch of the at least one retaining member from the locking groove when one of the plunger engagement sleeves and the plunger engagement post is movable to the disengaged position.

[0037] According to some embodiments, the fluid injector system may further include the syringe having: a barrel having a proximal end, a distal end having a discharge nozzle, and a barrel sidewall extending between the proximal end and the distal end; and a plunger slidably disposed within the barrel and reciprocating between the proximal end and the distal end.

[0038] According to some embodiments, the plunger may include: a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal end and the distal end; and the at least one retaining member associated with the plunger body and extending from the proximal end of the plunger body.

[0039] According to some embodiments, the at least one retaining member may include: a first end connected to the plunger body; a second end adjacent to the first end and radially and resiliently deflectable relative to the first end; and at least one lever located on the second end, wherein the at least one retaining member may have an outer surface configured to engage a plunger engagement sleeve when the plunger is engageable with the piston, wherein the at least one retaining member may have an inner surface configured to engage a plunger engagement post when the plunger is engageable with the piston, wherein the at least one lever may be configured to engage a locking feature on either the plunger engagement sleeve or the plunger engagement post when the plunger is engageable with the piston to prevent axial movement of the plunger relative to the piston, and wherein the at least one lever may be configured to radially deflect the second end of the at least one retaining member after axial movement of the piston relative to the plunger in a disengaged state, due to contact between the at least one lever and the locking feature.

[0040] According to some embodiments, the plunger can be configured to engage the plunger engagement mechanism regardless of the angular orientation of the plunger relative to the piston of the fluid injector.

[0041] According to some embodiments, the at least one lever may protrude radially inward from the inner surface of the at least one retaining member in one direction toward the central longitudinal axis, and the at least one lever may be configured to be received within the locking feature when the plunger is in the locked state with the piston, the locking feature being shaped as a locking groove protruding radially inward from one outer surface of the plunger engagement post.

[0042] According to some embodiments, the at least one lever may protrude radially inward from the inner surface of the at least one retaining member in one direction toward the central longitudinal axis, or the at least one lever may protrude radially outward from the outer surface of the at least one retaining member in one direction away from the central longitudinal axis. The at least one lever may define a locking groove for receiving at least a portion of the plunger engagement mechanism when the plunger can be connected to the piston. According to some embodiments, the plunger body may have a conical portion at the distal end and a cylindrical portion at the proximal end. The at least one retaining member may protrude from the proximal end of one inner surface of the conical portion. A plurality of release lugs may protrude radially inward from or from the proximal end of the inner surface of one inner surface of the cylindrical portion, each of the plurality of release lugs being configured to interact with the plunger engagement sleeve to release the plunger from the piston after the plunger has rotated about the central longitudinal axis. The proximal end of each of the plurality of release lugs may have a pointed guide surface.

[0043] Further embodiments or features of the present invention are described in the following numbered entries:

[0044] Clause 1: A plunger for use with a syringe, the plunger comprising: a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal end and the distal end; and at least one retaining member associated with the plunger body and extending from the proximal end of the plunger body, the at least one retaining member comprising: a first end connected to the plunger body; a second end proximal to the first end and radially and resiliently deflectable relative to the first end; and at least one lever located on the second end, wherein the at least one retaining member has a plunger engagement sleeve configured to engage a plunger engagement mechanism on a piston of a fluid injector system when the plunger and piston are in a locked state. One of the outer surfaces, wherein the at least one retaining member has an inner surface of a plunger engagement post of a plunger engagement mechanism configured to engage the plunger engagement mechanism when the plunger and the piston are in the locked state, wherein the at least one lever is configured to engage a locking feature on one of the plunger engagement sleeves and the plunger engagement post to prevent axial movement of the plunger relative to the piston when the plunger and the piston are in the locked state, and wherein the at least one lever is configured to radially deflect the second end of the at least one retaining member after the piston has moved axially relative to the plunger in an unlocked state, due to engagement of the at least one lever with the locking feature on one of the plunger engagement sleeves and the plunger engagement post.

[0045] Clause 2. The plunger as in Clause 1, wherein the at least one retaining member comprises a plurality of retaining members spaced apart around the central longitudinal axis.

[0046] Clause 3. The plunger as in Clause 2, wherein the plurality of retaining members are spaced apart at equal intervals around the central longitudinal axis.

[0047] Clause 4. A plunger as described in any of Clauses 1 to 3, wherein the at least one retaining member extends proximally in a direction parallel to the central longitudinal axis.

[0048] Clause 5. A plunger as described in any of Clauses 1 to 3, wherein the at least one retaining member extends proximally in one of the directions at an angle relative to the central longitudinal axis.

[0049] Clause 6. A plunger as described in any of Clauses 1 to 5, wherein the at least one retaining member is linearly connected between the first end and the second end.

[0050] Clause 7. A plunger as described in any of Clauses 1 to 5, wherein the at least one retaining member is connected by a curve between the first end and the second end.

[0051] Clause 8. A plunger as described in any of Clauses 1 to 7, wherein the plunger is configured to engage the plunger engagement mechanism regardless of the angular orientation of the plunger relative to the piston of the fluid injector.

[0052] Clause 9. A plunger as described in any one of Clauses 1 to 8, wherein the at least one lever has a first surface at a proximal end of the at least one lever configured to engage one of the plunger engagement sleeve and the plunger engagement post during plunger engagement with the piston, and a second surface at a distal end of the at least one lever configured to engage one of the plunger engagement sleeve and the plunger engagement post during plunger disengagement from the piston, at the proximal end of the locking feature.

[0053] Clause 10. A plunger as described in any of Clauses 1 to 9, wherein the at least one lever protrudes radially inward from the inner surface of the at least one retaining member in one of the directions toward the central longitudinal axis.

[0054] Clause 11. The plunger of any one of Clauses 1 to 10, wherein the at least one lever protrudes radially outward from the outer surface of the at least one retaining member in a direction away from the central longitudinal axis.

[0055] Clause 12. The plunger of any one of Clauses 1 to 11, wherein the at least one lever defines a locking groove for receiving at least a portion of the plunger engagement mechanism when the plunger is connected to the piston.

[0056] Clause 13. A plunger as described in any of Clauses 1 to 12, wherein the at least one lever protrudes radially inward from the inner surface of the at least one retaining member in a direction toward the central longitudinal axis, and wherein the at least one lever is configured to be received within the locking feature when the plunger and the piston are in the locked state, the locking feature being shaped as a locking groove protruding radially inward from the outer surface of one of the plunger engagement posts.

[0057] Clause 14. A plunger as described in any of Clauses 1 to 13, wherein the plunger body has a conical portion at the distal end and a cylindrical portion at the proximal end.

[0058] Clause 15. The plunger of Clause 14, wherein the at least one retaining member protrudes from the proximal end of one of the inner surfaces of the conical portion.

[0059] Clause 16. The plunger of Clause 14 or 15 further includes a plurality of release lugs that project radially inward from one inner surface of the cylindrical portion or proximal to the inner surface of the cylindrical portion, each of the plurality of release lugs being configured to interact with a plunger engagement sleeve to release the plunger from the piston after the plunger has rotated about the central longitudinal axis.

[0060] Clause 17. The plunger as in Clause 16, wherein one of the plurality of release lugs has a pointed guide surface at its proximal end.

[0061] Clause 18. The plunger of any one of Clauses 1 to 17 further includes a plunger cap that covers at least a portion of a distal surface of the plunger body and includes a seal disposed around at least a portion of the circumferential sidewall of the plunger body.

[0062] Clause 19. The plunger of any of Clauses 1 to 18, wherein the plunger is configured to be slidably positioned within a barrel of a syringe.

[0063] Clause 20. The plunger as in Clause 19, wherein the plunger is configured for reciprocating movement within the barrel of the syringe.

[0064] Clause 21. A fluid injector system comprising: at least one reciprocating piston having a piston head; and a plunger engagement mechanism associated with the piston head and configured to engage a plunger connected to a syringe of the fluid injector system for reciprocatingly driving the plunger in the syringe due to movement of the at least one piston, the plunger engagement mechanism comprising: a plunger engagement sleeve having a hollow body; a plunger engagement post received within the hollow body of the plunger engagement sleeve; and an actuator operatively connected to one of the plunger engagement sleeve and the plunger engagement post. Furthermore, it is configured to move one of the plunger engagement sleeve and the plunger engagement post between an engaged position and a disengaged position, wherein in the engaged position, the plunger engagement post is positioned within the hollow body of the plunger engagement sleeve to capture at least one resilient flexible retaining member associated with the plunger in a receiving space between the plunger engagement collar and the plunger engagement post, and wherein in the disengaged position, the plunger engagement post is at least partially positioned outside the hollow body of the plunger engagement sleeve to allow flexible insertion or removal of the at least one resilient flexible retaining member of the plunger from the receiving space.

[0065] Clause 22. The fluid injector system of Clause 21, wherein the actuator is a rotary electric motor, a linear electric motor, a linear actuator or a solenoid.

[0066] Clause 23. The fluid injector system as described in Clause 21, wherein the actuator is manually operated.

[0067] Clause 24. A fluid injector system as described in any of Clauses 21 to 23, wherein the actuator has an engaged state for moving one of the plunger engagement sleeve and the plunger engagement pin to the engaged position and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement pin to the disengaged position.

[0068] Clause 25. A fluid injector system as described in any of Clauses 21 to 24, wherein the actuator automatically moves to the disengaged state during the period when the actuator is de-energized.

[0069] Clause 26. A fluid injector system as described in any of Clauses 21 to 25, wherein the actuator is in the engaged state only during proximal movement of the at least one piston.

[0070] Clause 27. A fluid injector system as described in any of Clauses 21 to 26, further comprising at least one biasing element for moving the actuator from the engaged state to the disengaged state.

[0071] Clause 28. A fluid injector system as described in any of Clauses 21 to 27, wherein rotational movement of the actuator causes one of the plunger engagement sleeve and the plunger engagement post to move proximal or distal in a linear direction.

[0072] Clause 29. A fluid injector system as described in any of Clauses 21 to 28, wherein linear movement of the actuator causes one of the plunger engagement sleeve and the plunger engagement post to move proximal or distal in a linear direction.

[0073] Clause 30. A fluid injector system as described in any of Clauses 21 to 29, wherein the actuator is operatively connected to a controller configured to control the actuation of the actuator.

[0074] Clause 31. A fluid injector system as described in any of Clauses 21 to 30, wherein one of the plunger engagement sleeve and the plunger engagement pin is linearly or rotatably movable relative to the piston, while the other of the plunger engagement sleeve and the plunger engagement pin is stationary relative to the piston.

[0075] Clause 32. A fluid injector system as described in any of Clauses 21 to 31, wherein the plunger engagement post and the plunger engagement collar are linearly or rotatably movable relative to the piston.

[0076] Clause 33. The fluid injector system of any one of Clauses 21 to 32 further includes at least one sensor configured to detect a position of at least one of the plunger engagement collar and the plunger engagement post between the engagement position and the disengagement position.

[0077] Clause 34. A fluid injector system as described in any of Clauses 21 to 33, further comprising a plunger detection sensor configured to detect the presence of at least one retaining member of the plunger in the receiving space between the plunger engagement collar and the plunger engagement post.

[0078] Clause 35. A fluid injector system as described in any of Clauses 21 to 34, wherein the hollow body of the plunger engagement sleeve has an opening having a stepped inner diameter that decreases in the direction from one distal end of the plunger engagement sleeve to one proximal end of the plunger engagement sleeve.

[0079] Clause 36. A fluid injector system of any one of Clauses 21 to 35, wherein the plunger engagement post includes a locking groove that protrudes radially inward from one outer surface of the plunger engagement post, and wherein the locking groove is configured to receive at least one latch on the at least retaining member of the plunger.

[0080] Clause 37. A fluid injector system as described in Clause 36, wherein a distal edge of the locking groove is configured to flexibly deflect the at least one retaining member of the plunger during axial movement of the plunger relative to the piston, so as to disengage the at least one latch of the at least one retaining member from the locking groove when one of the plunger engagement sleeve and the plunger engagement post moves to the disengaged position.

[0081] Clause 38. A fluid injector system as described in any of Clauses 21 to 37, wherein the plunger engagement post has a body having a stepped outer diameter that decreases in the direction from a distal end of the plunger engagement post to a proximal end of the plunger engagement post.

[0082] Clause 39. A fluid injector system of any one of Clauses 21 to 38, wherein the plunger engagement collar includes a locking feature that protrudes radially inward from one inner surface of the plunger engagement collar, and wherein the locking feature is configured to engage at least one latch on the at least retaining member of the plunger when one of the plunger engagement sleeve and the plunger engagement post is moved to the engagement position.

[0083] Clause 40. A fluid injector system as described in Clause 39, wherein the locking feature is configured to flexibly deflect the at least one retaining member of the plunger during axial movement of the plunger relative to the piston so that when one of the plunger engagement sleeve and the plunger engagement post moves to the disengaged position, the at least one lever of the at least one retaining member moves away from the locking feature.

[0084] Clause 41. The fluid injector system of any one of Clauses 21 to 39 further includes the syringe, the syringe comprising: a barrel having a proximal end, a distal end having a discharge nozzle, and a barrel sidewall extending between the proximal end and the distal end; and a plunger slidably disposed within the barrel and reciprocating between the proximal end and the distal end.

[0085] Clause 42. The fluid injector system of Clause 41, wherein the plunger includes: a plunger body defining a central longitudinal axis and having a proximal end, a distal end and a circumferential sidewall connecting the proximal end and the distal end; and the at least one retaining member associated with the plunger body and extending from the proximal end of the plunger body.

[0086] Clause 43. A fluid injector system as described in Clause 41 or 42, wherein the at least one retaining member comprises: a first end connected to the plunger body; a second end adjacent to the first end and radially and resiliently deflectable relative to the first end; and at least one lever located on the second end, wherein the at least one retaining member has an outer surface configured to engage a plunger engagement sleeve when the plunger engages with the piston, wherein the at least one retaining member has an inner surface configured to engage a plunger engagement post when the plunger engages with the piston, wherein the at least one lever is configured to engage a locking feature on either the plunger engagement sleeve or the plunger engagement post when the plunger engages with the piston to prevent axial movement of the plunger relative to the piston, and wherein the at least one lever is configured to radially deflect the second end of the at least one retaining member after axial movement of the piston relative to the plunger in a disengaged state, due to contact between the at least one lever and the locking feature.

[0087] Clause 44. A fluid injector system as described in any of Clauses 41 to 43, wherein the plunger is configured to engage the plunger engagement mechanism regardless of the angular orientation of the plunger relative to the piston of the fluid injector.

[0088] Clause 45. A fluid injector system as described in any of Clauses 41 to 44, wherein the at least one lever protrudes radially inward from the inner surface of the at least one retaining member in one direction toward the central longitudinal axis, and wherein the at least one lever is configured to be received within a locking feature when the plunger and the piston are in the locked state, the locking feature being shaped as a locking groove protruding radially inward from one outer surface of the plunger engagement post.

[0089] Clause 46. A fluid injector system as described in any of Clauses 41 to 45, wherein the at least one lever protrudes radially inward from the inner surface of the at least one retaining member in one direction toward the central longitudinal axis, or wherein the at least one lever protrudes radially outward from the outer surface of the at least one retaining member in one direction away from the central longitudinal axis.

[0090] Clause 47. A fluid injector system as described in any of Clauses 41 to 46, wherein the plunger body has a conical portion at the distal end and a cylindrical portion at the proximal end.

[0091] Clause 48. A fluid injector system as described in Clause 47, wherein the at least one retaining member protrudes from the proximal end of one of the inner surfaces of the conical portion.

[0092] Clause 49. The fluid injector system of Clause 47 or 48 further includes a plurality of release lugs projecting radially inward from one inner surface of the cylindrical portion, each of the plurality of release lugs being configured to interact with the plunger engagement sleeve to release the plunger from the piston after the plunger has rotated about the central longitudinal axis.

[0093] Clause 50. A fluid injector system as described in Clause 49, wherein one of the plurality of release lugs has a pointed guide surface at its proximal end.

[0094] Clause 51. A fluid injector system comprising: at least one reciprocating piston having a piston head; and a plunger engagement mechanism associated with the piston head and configured to engage a plunger connected to a syringe of the fluid injector system for reciprocatingly driving the plunger in the syringe due to movement of the at least one piston, the plunger engagement mechanism comprising: a plunger engagement sleeve having a hollow body including a longitudinal axis; and a plunger engagement post received in the hollow body of the plunger engagement sleeve and axially movable relative to the plunger engagement sleeve between an engaged position and a disengaged position, wherein the plunger engagement sleeve is rotatable about the longitudinal axis between a first position and a second position, and wherein the plunger engagement post is axially movable along the longitudinal axis from the engaged position to the disengaged position via rotation of the plunger engagement sleeve.

[0095] Clause 52. The fluid injector system of Clause 51, wherein the plunger engagement post is axially movable from one proximal end of the piston toward one distal end of the piston.

[0096] Clause 53. A fluid injector system as described in 51 or 52, wherein the plunger release sleeve includes a plurality of plunger release teeth that project radially outward from one of the outer surfaces of the hollow body.

[0097] Clause 54. A fluid injector system as described in Clause 53, wherein the plurality of plunger release teeth are configured to engage a plurality of release lugs on the plunger, such that rotation of the plunger about a longitudinal axis causes rotation of the plunger engagement sleeve about the longitudinal axis.

[0098] Clause 55. A fluid injector system as described in any of Clauses 51 to 54, further comprising a plunger release sleeve surrounding at least a portion of the plunger engagement sleeve, wherein the plunger release sleeve is configured to rotate about the longitudinal axis as the plunger engagement sleeve rotates.

[0099] Clause 56. A fluid injector system as described in any of Clauses 51 to 55, wherein the plunger release sleeve includes an opening having an inclined surface at an angle relative to a direction of the longitudinal axis in a direction from a distal end of the plunger release sleeve toward a proximal end of the plunger release sleeve.

[0100] Clause 57. A fluid injector system as described in Clause 56, wherein the plunger engagement post has a guide pin extending in a direction perpendicular to the longitudinal axis, and wherein the guide pin is received within the opening of the plunger release sleeve.

[0101] Clause 58. A fluid injector system as described in Clause 57, wherein rotation of the plunger engagement sleeve causes a corresponding rotation of one of the plunger release sleeves, and wherein the guide pin is guided along the inclined surface from a proximal end of one of the inclined surfaces toward a distal end, thereby moving the plunger engagement pin from the engagement position to the disengagement position.

[0102] Clause 59. The fluid injector system of any one of Clauses 51 to 58 further includes a biasing member operably connected to the plunger engagement sleeve and the plunger engagement post.

[0103] Clause 60. A fluid injector system as described in Clause 59, wherein the biasing member is configured to bias the plunger engagement sleeve to the first position.

[0104] Clause 61. A fluid injector system as described in any of Clauses 51 to 60, further comprising an actuator operably connected to the plunger engagement post and configured to move the plunger engagement post between the engagement position and the disengagement position.

[0105] Clause 62. The fluid injector system of Clause 61, wherein in the engaged position, the plunger engagement post is positioned within the hollow body of the plunger engagement sleeve and configured to capture at least one resilient flexible retaining member associated with the plunger in a receiving space between the plunger engagement collar and the plunger engagement post, and wherein in the disengaged position, the plunger engagement post is at least partially positioned outside the hollow body of the plunger engagement sleeve to allow flexible insertion or removal of the at least one resilient flexible retaining member of the plunger from the receiving space.

[0106] Clause 63. A fluid injector system as described in Clause 61 or 62, wherein the actuator is a rotary electric motor, a linear electric motor, a linear actuator, or a solenoid.

[0107] Clause 64. A fluid injector system as described in any of Clauses 61 to 63, wherein the actuator is manually operated.

[0108] Clause 65. A fluid injector system of any one of Clauses 61 to 63, wherein the actuator has an engaged state for moving one of the plunger engagement sleeve and the plunger engagement pin to the engaged position and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement pin to the disengaged position.

[0109] Clause 66. A fluid injector system as described in any of Clauses 61 to 65, wherein the actuator automatically moves to the disengaged state during the period when the actuator is de-energized.

[0110] Clause 67. A fluid injector system as described in any of Clauses 61 to 66, wherein the actuator is in the engaged state only during proximal movement of the at least one piston.

[0111] Clause 68. A fluid injector system as described in any of Clauses 61 to 67, further comprising at least one biasing element for moving the actuator from the engaged state to the disengaged state.

[0112] Clause 69. A fluid injector system as described in any of Clauses 61 to 68, wherein rotational movement of the actuator causes one of the plunger engagement sleeve and the plunger engagement post to move proximal or distal in a linear direction.

[0113] Clause 70. A fluid injector system as described in any of Clauses 61 to 69, wherein linear movement of the actuator causes one of the plunger engagement sleeve and the plunger engagement post to move proximal or distal in a linear direction.

[0114] Clause 71. A fluid injector system as described in any of Clauses 61 to 70, wherein the actuator is operatively connected to a controller configured to control the actuation of the actuator.

[0115] Clause 72. The fluid injector system of any one of Clauses 51 to 71 further includes at least one sensor configured to detect a position of at least one of the plunger engagement collar and the plunger engagement post between the engagement position and the disengagement position.

[0116] Clause 73. The fluid injector system of Clauses 51 to 72 further includes a plunger detection sensor configured to detect the presence of at least one retaining member of the plunger in the receiving space between the plunger engagement collar and the plunger engagement post.

[0117] Clause 74. A fluid injector system as described in any of Clauses 51 to 73, wherein the hollow body of the plunger engagement sleeve has an opening having a stepped inner diameter that decreases in the direction from one distal end of the plunger engagement sleeve to one proximal end of the plunger engagement sleeve.

[0118] Clause 75. A fluid injector system of any one of Clauses 51 to 74, wherein the plunger engagement post includes a locking groove that projects radially inward from one of the outer surfaces of the plunger engagement post, and wherein the locking groove is configured to receive at least one latch on at least one retaining member of the plunger.

[0119] Clause 76. A fluid injector system as described in Clause 75, wherein a distal edge of the locking groove is configured to flexibly deflect the at least one retaining member of the plunger during axial movement of the plunger relative to the piston, so as to disengage the at least one latch of the at least one retaining member from the locking groove when one of the plunger engagement sleeve and the plunger engagement post moves to the disengaged position.

[0120] Clause 77. The fluid injector system of any one of Clauses 51 to 76 further includes the injector comprising: a barrel having a proximal end, a distal end having a discharge nozzle, and a barrel sidewall extending between the proximal end and the distal end; and a plunger slidably disposed within the barrel and reciprocating between the proximal end and the distal end.

[0121] Clause 78. A fluid injector system as described in Clause 77, wherein the plunger includes: a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal end and the distal end; and the at least one retaining member associated with the plunger body and extending from the proximal end of the plunger body.

[0122] Clause 79. A fluid injector system as described in Clauses 77 or 78, wherein the at least one retaining member comprises: a first end connected to the plunger body; a second end adjacent to the first end and radially and resiliently deflectable relative to the first end; and at least one lever located on the second end, wherein the at least one retaining member has an outer surface configured to engage a plunger engagement sleeve when the plunger engages with the piston, wherein the at least one retaining member has an inner surface configured to engage a plunger engagement post when the plunger engages with the piston, wherein the at least one lever is configured to engage a locking feature on either the plunger engagement sleeve or the plunger engagement post when the plunger engages with the piston to prevent axial movement of the plunger relative to the piston, and wherein the at least one lever is configured to radially deflect the second end of the at least one retaining member after axial movement of the piston relative to the plunger in a disengaged state, due to contact between the at least one lever and the locking feature.

[0123] Clause 80. A fluid injector system as described in any of Clauses 77 to 79, wherein the plunger is configured to engage the plunger engagement mechanism regardless of the angular orientation of the plunger relative to the piston of the fluid injector.

[0124] Clause 81. A fluid injector system as described in any of Clauses 77 to 80, wherein the at least one lever protrudes radially inward from the inner surface of the at least one retaining member in a direction toward the central longitudinal axis, and wherein the at least one lever is configured to be received within a locking feature when the plunger and the piston are in the locked state, the locking feature being shaped as a locking groove protruding radially inward from the outer surface of one of the plunger engagement posts.

[0125] Clause 82. A fluid injector system as described in any of Clauses 77 to 81, wherein the at least one lever protrudes radially inward from the inner surface of the at least one retaining member in a direction toward the central longitudinal axis, or wherein the at least one lever protrudes radially outward from the outer surface of the at least one retaining member in a direction away from the central longitudinal axis.

[0126] Clause 83. A fluid injector system as described in any of Clauses 77 to 82, wherein the at least one lever defines a locking groove for receiving at least a portion of the plunger engagement mechanism when the plunger is connected to the piston.

[0127] Clause 84. A fluid injector system as described in any of Clauses 77 to 83, wherein the plunger body has a conical portion at the distal end and a cylindrical portion at the proximal end.

[0128] Clause 85. A fluid injector system as described in Clause 84, wherein the at least one retaining member protrudes from the proximal end of one of the inner surfaces of the conical portion.

[0129] Clause 86. The fluid injector system of Clause 84 or 85 further includes a plurality of release lugs that project radially inward from one inner surface of the cylindrical portion or proximal to the inner surface of the cylindrical portion, each of the plurality of release lugs being configured to interact with the plunger engagement sleeve to release the plunger from the piston after the plunger has rotated about the central longitudinal axis.

[0130] Clause 87. A fluid injector system as described in Clause 86, wherein one of the plurality of release lugs has a pointed guide surface at its proximal end.

[0131] The functionality and combination of related elements and manufacturing economy of such and other features and characteristics, operating methods and structures of syringes, syringe plungers, pressure jackets and systems having syringes and / or syringe plungers will become clearer from the following description with reference to the accompanying drawings, all of which form part of this specification, wherein like element symbols indicate corresponding parts in the various figures. However, it should be clearly understood that the drawings are for illustration and description only. Simple Explanation of the Diagram

[0132] Figure 1 is a perspective view of a fluid injector system according to one embodiment of the present invention;

[0133] Figure 2 is a schematic diagram of one of the fluid injector systems shown in Figure 1;

[0134] Figure 3 is a perspective view of a fluid injector system according to another embodiment of the present invention;

[0135] Figure 4 is a schematic diagram of a controller of a fluid injector system according to one embodiment of the present invention;

[0136] Figure 5A is a perspective view of a syringe according to one embodiment of the present invention;

[0137] Figure 5B is a cross-sectional view of one of the syringes in Figure 5A, showing a plunger positioned inside one barrel of the syringe;

[0138] Figure 6 is an exploded perspective view of a plunger according to one embodiment of the present invention;

[0139] Figure 7 is a perspective cross-sectional view of one of the support rings of the plunger in Figure 6;

[0140] Figure 8A is a cross-sectional perspective view of a support ring of a plunger according to another embodiment of the present invention;

[0141] Figure 8B is a cross-sectional perspective view of a support ring of a plunger according to another embodiment of the present invention;

[0142] Figure 8C is a cross-sectional perspective view of a support ring of a plunger according to another embodiment of the present invention;

[0143] Figure 9 is a perspective cross-sectional view of a piston in a plunger engagement mechanism according to an embodiment of the present invention;

[0144] Figure 10A is a perspective view of one of the plunger engagement sleeves in the plunger engagement mechanism shown in Figure 9;

[0145] Figure 10B is a cross-sectional view of one of the plunger engagement sleeves shown in Figure 10A;

[0146] Figure 11A is a perspective view of an actuator and a plunger release sleeve of the plunger engagement mechanism shown in Figure 9;

[0147] Figure 11B is a cross-sectional view of one of the actuators and plunger release sleeves shown in Figure 11A;

[0148] Figure 12 is a perspective view of one of the plunger engagement pins of the plunger engagement mechanism shown in Figures 9 and 13A to 13J;

[0149] Figures 13A to 13J are perspective cross-sectional views of the operation of the piston and plunger engagement mechanism in Figure 9;

[0150] Figures 14A to 14C are cross-sectional views of the operation of a piston in a plunger engagement mechanism according to another embodiment of the present invention;

[0151] Figure 15 is a perspective view of one of the plunger engagement columns of one of the plunger engagement mechanisms shown in Figures 14A to 14C;

[0152] Figure 16 is a perspective view of a plunger release sleeve of one of the plunger engagement mechanisms shown in Figures 14A to 14C;

[0153] Figures 17A and 17B are perspective views (Figure 17A) and perspective cross-sectional views (Figure 17B) of a plunger engagement sleeve in one of the plunger engagement mechanisms shown in Figures 14A to 14C.

[0154] Figure 18A is a perspective cross-sectional view of the operation of a piston in a plunger engagement mechanism according to another embodiment of the present invention;

[0155] Figure 18B is a perspective view of one of the plunger engagement pins in the plunger engagement mechanism shown in Figure 18A;

[0156] Figure 19 is a perspective view of a piston in a fluid injector system having a plunger engagement mechanism according to another embodiment of the present invention;

[0157] Figure 20 is an exploded perspective view of one of the plunger engagement mechanisms in Figure 19;

[0158] Figures 21A and 21B are cross-sectional views of the operation of the plunger engagement mechanism in Figure 19;

[0159] Figures 22A to 22E are cross-sectional views of the operation of a plunger engagement mechanism according to another embodiment of the present invention;

[0160] Figures 23A to 23G are cross-sectional views of a piston in operation of a plunger engagement mechanism according to another embodiment of the present invention;

[0161] Figure 24A is a perspective view of a piston having a plunger engagement mechanism according to another embodiment of the present invention;

[0162] Figure 24B is an exploded view of one of the plunger engagement mechanisms in Figure 24A;

[0163] Figure 24C is a cross-sectional view of one of the piston and plunger engagement mechanisms in Figure 24A;

[0164] Figures 25A and 25B are cross-sectional views of a piston in operation of a plunger engagement mechanism according to another embodiment of the present invention;

[0165] Figure 26 is a perspective cross-sectional view of a piston in a fluid injector system having a plunger engagement mechanism according to another embodiment of the present invention;

[0166] Figures 27A and 27B are perspective views (Figure 27A) and a perspective cross-sectional view (Figure 27B) of one of the plunger engagement sleeves in the plunger engagement mechanism of Figure 26;

[0167] Figure 28 is a perspective view of one of the plunger release sleeves in the plunger engagement mechanism of Figure 26;

[0168] Figure 29 is a perspective cross-sectional view of one of the plunger engagement pins in the plunger engagement mechanism shown in Figure 26;

[0169] Figures 30A to 30D are perspective cross-sectional views of the engagement operation of the piston and plunger engagement mechanism in Figure 26, showing the plunger engagement mechanism in various stages during plunger engagement;

[0170] Figures 31A to 31D are perspective cross-sectional views of the piston and plunger engagement mechanism of Figure 26 during disengagement, showing the plunger engagement mechanism at various stages during plunger disengagement;

[0171] Figure 32 is a top view of a system including a fluid injector and a pressure sheath according to another embodiment of the present invention;

[0172] Figure 33 is an exploded top view of one of the systems in Figure 32;

[0173] Figure 34 is a perspective view of a pressure sheath according to another embodiment of the present invention;

[0174] Figure 35A is a perspective view of a syringe cap according to another embodiment of the present invention; and

[0175] Figure 35B is a perspective view of a syringe assembly according to another embodiment of the present invention. Implementation

[0176] Cross-reference to related applications This application claims priority to U.S. Provisional Application No. 62 / 705,265, filed June 18, 2020, the entire contents of which are incorporated herein by reference.

[0177] For the purposes of the following description, the terms "up," "down," "right," "left," "vertical," "horizontal," "top," "bottom," "lateral," "longitudinal," and their derivatives should be used in connection with this invention because of their orientation in the diagrams. Spatial or directional terms (such as "left," "right," "inside," "outside," "above," "below," and the like) should not be considered limiting, as the embodiments described herein may present various alternative orientations.

[0178] As used herein, unless otherwise expressly stated herein, the singular forms of “a” and “the” include the plural referents. All numbers used in the specification and claims should be understood to be modified by the term “about” in all instances. The terms “approximately,” “about,” and “substantially” mean a range of ±10% of the stated value.

[0179] Unless otherwise indicated, all ranges or ratios disclosed herein should be understood to encompass start and end values ​​and any and all subranges or subratios contained therein. For example, a range or ratio described as "1 to 10" should be considered as encompassing any and all subranges or subratios between a minimum value of 1 and a maximum value of 10 (and including both the minimum value of 1 and the maximum value of 10), that is, all subranges or subratios that begin with a minimum value of 1 or greater and end with a maximum value of 10 or less. The ranges and / or ratios disclosed herein represent average values ​​within the specified ranges and / or ratios.

[0180] As used herein, the term "at least one of..." is synonymous with "one or more of...". For example, the phrase "at least one of A, B, and C" means any one of A, B, and C, or any combination of any two or more of A, B, and C. For example, "at least one of A, B, and C" includes only one or more of A, or only one or more of B, or only one or more of C, or one or more of A and one or more of B, or one or more of A and one or more of C, or one or more of B and one or more of C, or all one or more of A, B, and C. Similarly, as used herein, the term "at least two of..." is synonymous with "two or more of...". For example, the phrase "at least two of D, E, and F" means any combination of any two or more of D, E, and F. For example, "at least two of D, E and F" includes one or more of D and one or more of E, or one or more of D and one or more of F, or one or more of E and one or more of F, or all of D, E and F.

[0181] The terms "first," "second," and similar terms are not intended to refer to any particular order or sequence, but rather to different conditions, properties, or elements. The entire contents of all documents cited herein are incorporated herein by reference. The term "at least" is synonymous with "greater than or equal to." The term "not greater than" is synonymous with "less than or equal to."

[0182] It should be understood that, unless expressly stated otherwise, the present invention may present alternative variations and sequences of steps. It should also be understood that the specific apparatus and procedures illustrated in the drawings and described in the following description are merely illustrative examples of the invention. Therefore, specific dimensions and other physical characteristics relating to the examples disclosed herein should not be considered as limitations.

[0183] As used herein, the term "parallel" or "substantially parallel" means a relative angle between two objects (if extended to theoretical intersection) (such as slender objects and including reference lines), ranging from 0° to 5°, or from 0° to 3°, or from 0° to 2°, or from 0° to 1°, or from 0° to 0.5°, or from 0° to 0.25°, or from 0° to 0.1°, including the listed values.

[0184] As used herein, the term "perpendicular" or "substantially perpendicular" means that the relative angle between two objects at one of their actual or theoretical points of intersection is from 85° to 90°, or from 87° to 90°, or from 88° to 90°, or from 89° to 90°, or from 89.5° to 90°, or from 89.75° to 90°, or from 89.9° to 90°, including the values ​​listed.

[0185] When used relative to a component of a fluid delivery system (such as a fluid reservoir, syringe, pressure sheath, or fluid line), the term "distal" refers to the portion of that component closest to a patient. When used relative to a component of an injector system (such as a fluid reservoir, syringe, pressure sheath, or fluid line), the term "proximal" refers to the portion of that component closest to the injector of the injector system (i.e., the portion of that component furthest from the patient). When used relative to a component of a fluid delivery system (such as a fluid line), the term "upstream" refers to a direction away from the patient and towards the injector of the injector system. For example, if a first component is referred to as "upstream" of a second component, the first component is located closer to the injector than the second component. When used relative to a component of a fluid delivery system (such as a fluid line), the term "downstream" refers to a direction towards the patient and away from the injector of the fluid delivery system. For example, if a first component is referred to as "downstream" of a second component, the first component is located closer to the patient than the second component.

[0186] When used relative to the movement of components of a fluid delivery system (such as one or more components of a plunger engagement mechanism associated with a piston), the term "automatic" or "automatically" means the movement of one or more components without manual assistance.

[0187] Although the systems and devices described herein are referenced to computed tomography (CT) contrast injection systems, angiography (CV) contrast injection systems, positron emission tomography (PET) contrast injection systems and magnetic resonance imaging (MRI) contrast injection systems, other pressurized injection protocols may also be incorporated into the various embodiments described herein for securing a syringe plunger to a piston of a fluid injector.

[0188] Referring to the same element symbols which refer to the same portions in all the views, the present invention is generally directed to a syringe plunger and a connection interface for connecting the syringe plunger to a piston of a fluid injector. Various embodiments are directed to a syringe plunger that can be connected to and disconnected from a piston. In various embodiments, such pistons can be manually, mechanically, hydraulically, or electrically actuated. Furthermore, the present invention provides a quick and easy solution for engaging and / or disengaging a syringe plunger from a piston without requiring a specific rotational orientation or alignment of the plunger relative to the piston. For example, the piston can be advanced forward until it engages with the plunger, regardless of the plunger's orientation about its longitudinal axis relative to the piston's longitudinal axis, as will be described in more detail herein. Additionally, when the piston is attachable to the plunger, a simple rotation of the plunger (e.g., of the syringe) about its longitudinal axis relative to the piston can cause the two elements to disengage. In other embodiments, the engagement and disengagement of the piston and plunger can be performed by a fluid injector controller, such as automatically as part of a programmed injection protocol during the start and end of a fluid injection protocol, or initiated by a user, for example, through user input to a fluid injector controller. In further embodiments or embodiments, the invention is also generally directed to pressure sheaths and caps for pressure sheaths, wherein the same connection interface used for connecting the syringe plunger to the piston of the fluid injector can be used to connect the pressure sheath to the fluid injector and / or connect the cap of the pressure sheath to the pressure sheath itself.

[0189] Referring to Figure 1, a non-limiting example of a fluid injector system 10 (hereinafter referred to as "injector 10") (such as an automatic or electric fluid injector) is adapted to interface with and actuate at least one syringe 12 and a corresponding plunger 26, each of which can be independently filled with a medical fluid F, such as a contrast agent, saline, or any desired medical fluid. Injector 10 can be used during a medical procedure to inject medical fluid into a patient by actuating the plunger 26 of at least one syringe 12 using at least one actuating member (such as at least one piston 13 (shown in Figure 2)). Injector 10 can be a multi-syringe injector, wherein several syringes 12 can be oriented in a side-by-side or other relation and include plungers 26 individually actuated by their respective pistons 13 associated with injector 10. In embodiments having two syringes arranged in a side-by-side relation and filled with two different medical fluids, injector 10 can deliver fluid from one or both of the syringes 12.

[0190] The injector 10 may be enclosed within a housing 14 formed of a suitable structural material such as plastic or metal. The housing 14 may have various shapes and sizes depending on the application. The injector 10 includes at least one syringe port 16 for connecting at least one syringe 12 to a respective piston 13 (FIG. 2).

[0191] At least one fluid pathway 17 can be fluidly connected to at least one syringe 12 to deliver medical fluid F from at least one syringe 12 to a catheter, needle, or other fluid delivery connection (not shown) inserted into a patient at a vascular puncture site. The fluid flow from at least one syringe 12 can be regulated by a controller 200 (Figure 2). The controller 200 can operate various pistons, piston mechanics (such as components for engaging and disengaging a piston with a plunger), valves, and / or flow control mechanisms to regulate the delivery of medical fluids such as saline and contrast fluid to the patient based on user-selected injection parameters. One embodiment of a suitable preloaded fluid injector (which can be modified for use with the system described above, the system comprising at least one syringe and at least one piston for engaging and releasably retaining a plunger of one syringe engaged with the fluid injector described herein with reference to Figures 1 and 2) is disclosed in U.S. Patent No. 5,383,858, while another embodiment of a related multifluid delivery system (which can be modified for use with the system of the present invention) is found in U.S. Patent Nos. 7,553,294, 7,666,169, International Patent Application No. PCT / US2012 / 037491, and U.S. Publication No. 2014 / 0027009, the disclosures of which are incorporated herein by reference. Other embodiments may include novel fluid injector systems of various embodiments designed to include a connection interface between the piston 13 of the injector 10 described herein and the plunger 26 of the syringe 12.

[0192] Referring to Figure 3, a representative embodiment of a dual-syringe angiography injector system 100 (hereinafter referred to as "injector 100") is illustrated. Injector 100 is configured to inject two medical fluids through a first fluid path 17A for a medical fluid (such as an imaging contrast agent for an angiography injection procedure) and a second fluid path 17B for a flushing fluid (such as saline or Ringer's lactate). Injector 100 may include an injector housing 14 having two syringe ports 16 configured to engage two syringes 12.

[0193] The injector housing 14 may further include at least one user interface 11 through which an operator can view and control the status of an injection procedure. The user interface 11 may communicate with a controller (similar to the controller 200 described herein) that sends commands to and receives commands from the user interface 11.

[0194] The injector 100 may further include at least one upstream air detector 240 for detecting one or more air bubbles within an air detection tube region 250 of one of the first fluid paths 17A and the second fluid path 17B. The air detection tube region 250 may, for example, be associated with a proximal portion of one of the first fluid paths 17A and the second fluid path 17B. The at least one air detector 240 may include an ultrasonic sensor and an optical sensor, or the like, configured to detect one or more air bubbles within the fluid path.

[0195] Referring again to Figure 3, the injector 100 may further include bulk fluid containers 19A and 19B for filling and refilling the respective syringes 12 with imaging contrast agent and flushing fluid, respectively. Bulk fluid containers 19A and 19B may be selectively fluidly connected to the syringes 12 via respective bulk fluid paths 21A and 21B and bulk fluid valves 23A and 23B.

[0196] Further details and examples of suitable non-limiting electrically powered injector systems comprising syringes, controllers, and air detectors are described in U.S. Patent Nos. 5,383,858, 7,553,294, 7,666,169, 8,945,051, 10,022,493, and 10,507,319, the entire disclosure of which is incorporated herein by reference. Although injector 100 is described herein in the context of a dual-syringe angiography (CV) injector, it should be understood that injector 100 is adaptable to single-syringe and multi-syringe configurations for any injection procedure (e.g., CT, PET, MRI, ultrasound, etc.).

[0197] Injector 100 may include a piston associated with each of the syringes 12, similar to piston 13 described herein in Figure 2. Each piston is configured to drive a respective plunger within a barrel of its respective syringe 12. Due to the high pressure associated with CV angiography, syringe 12 may be inserted into a pressure sheath 15 to control the radial expansion of the syringe. A controller is operably associated with the piston to reciprocate the plunger within the syringe 12 and thereby perform an injection procedure.

[0198] The controller can be programmed or configured to perform a filling operation during which a piston associated with each syringe 12 is withdrawn toward the proximal end of one of the syringes 12 to draw injection fluid (e.g., imaging contrast agent and flushing fluid) from bulk fluid containers 19A, 19B into the syringe 12. During this filling operation, the controller can be programmed or configured to selectively actuate bulk fluid valves 23A and 23B to establish fluid communication between the respective syringe 12 and the bulk fluid containers 19A, 19B via bulk fluid paths 21A and 21B to control the filling of the syringe 12 with appropriate injection fluid. After the filling operation is completed and, where appropriate, the injection operation to remove any air from the syringe 12 (e.g., by injecting any such air back into the bulk fluid containers 19A, 19B or through an injection tube) is completed, the controller can be programmed or configured to selectively actuate the bulk fluid valves 23A and 23B to block fluid communication between the respective syringe 12 and the bulk fluid containers 19A, 19B via the bulk fluid paths 17A and 17B.

[0199] Following the filling and dispensing operations, the controller can be programmed or configured to perform a delivery operation during which a piston associated with one or both of the syringes 12 moves toward the distal end of one of the syringes 12 to inject fluid into a first fluid path 17A and a second fluid path 17B. The controller can be programmed or configured to selectively actuate fluid valves 23A and 23B to establish fluid communication between the syringe 12 and the patient via fluid paths 17A and 17B. According to various embodiments, the first fluid path 17A and the second fluid path 17B can be incorporated at a fluid mixing connector that provides turbulent mixing of the first and second fluids, such as the fluid mixing connector described in International PCT Applications PCT / US2021 / 019507 and PCT / US2014 / 026324, the disclosures of which are incorporated herein by reference.

[0200] Referring now to FIG4, a schematic diagram of an exemplary component of an embodiment of a controller 200 for implementing and performing the systems and methods described herein, according to an embodiment of the present invention, is shown. In some embodiments, the controller 200 may include additional components, fewer components, different components, or different configuration components compared to the controller shown in FIG4. The controller 200 may include a bus 202, at least one processor 204, memory 206, a storage component 208, an input component 210 (such as a GUI, keyboard, or other user interface 11 shown in FIG3), an output component 212 (such as a GUI or other user interface 11), and a communication interface 214 (such as a GUI or other user interface 11). The bus 202 may include a component that allows communication between the components of the controller 200. In some non-limiting embodiments, the at least one processor 204 may be implemented in hardware, firmware, or a combination of hardware and software. For example, at least one processor 204 may include a processor (e.g., a central processing unit (CPU), a graphics processing unit (GPU), an accelerated processing unit (APU), etc.), a microprocessor, a digital signal processor (DSP), and / or any processing component that can be programmed to perform a function (e.g., a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), etc.). Memory 206 may include random access memory (RAM), read-only memory (ROM), and / or another type of dynamic or static storage device (e.g., flash memory, magnetic memory, optical memory, etc.) that stores information and / or instructions used by at least one processor 204.

[0201] Storage component 208 may store information and / or software related to the operation and use of controller 200. For example, storage component 208 may include a hard drive and / or another type of computer-readable media. Input component 210 may include a component that allows controller 200 to receive information such as via user input (e.g., a GUI, a touch screen display, a keyboard, a keypad, a mouse, a button, a switch, a microphone, etc.). Alternatively, input component 210 may include a sensor for sensing information (e.g., a Global Positioning System (GPS) component, an accelerometer, a gyroscope, an actuator, etc.). Output component 212 may include a component that provides output information from controller 200 (e.g., a GUI, a display, a speaker, one or more light-emitting diodes (LEDs), etc.). Communication interface 214 may include transceiver components (e.g., a transceiver, a separate receiver and transmitter, etc.) that enable controller 200 to communicate with other devices, such as via a wired connection, a wireless connection, or a combination of wired and wireless connections. Communication interface 214 may allow controller 200 to receive information from another device and / or provide information to another device. Input component 210, output component 212, and / or communication interface 214 may correspond to user interface 11 or be components of user interface 11 (see Figure 3).

[0202] The controller 200 can execute the methods described herein by executing software instructions stored in a computer-readable medium (e.g., memory 206 and / or storage component 208) based on at least one processor 204. A computer-readable medium may contain any non-transitory memory device. A memory device may include memory space located within a single physical storage device or memory space distributed across multiple physical storage devices. Software instructions may be read into memory 206 and / or storage component 208 via communication interface 214 from another computer-readable medium or from another device. Software instructions stored in memory 206 and / or storage component 208 may, when executed, cause processor 204 to execute one or more programs described herein. Alternatively or additionally, a wired circuit system may be used in place of or in combination with software instructions to execute one or more programs described herein.

[0203] After describing the general structure and function of injectors 10 and 100, a non-limiting embodiment of a syringe 300 configured for use with injectors 10 of Figures 1 and 2 or injector 300 of Figure 3 will now be discussed in more detail with reference to Figures 5A and 5B. The syringe 300 generally has a cylindrical syringe barrel 318 formed of glass, metal, or a medical-grade plastic. The barrel 318 has a proximal end 320 and a distal end 324, and a sidewall 319 extending along a length of a syringe longitudinal axis 315 extending through the center of the barrel 318 between the proximal end 320 and the distal end 324 (as shown in Figure 5B). The barrel 318 may be made of a transparent or translucent material. A nozzle 322 extends from the distal end 324 of the barrel 318. As shown in Figure 5B, the barrel 318 has an outer surface 321 and an inner surface 323 defining an internal volume 325 therein for receiving fluid. The proximal end 320 of the cylinder 318 may be sealed using a plunger 326 that slides through the cylinder 318. As the plunger 326 advances through the cylinder 318, the plunger 326 forms a liquid-tight seal with the inner surface 323 of the sidewall 319 of the cylinder 318. The plunger 326 is configured to releasably engage one of the pistons of the fluid injectors 10, 100 according to the various engagement mechanisms described herein.

[0204] A droplet flange 335 extends radially outward from the outer surface 321 of the syringe barrel 318 and prevents fluid dripping from the nozzle 322 from entering the syringe port on the injector. In some embodiments, the droplet flange 335 defines a stop surface of the insertion section 330 of the syringe 300.

[0205] Referring to FIG5A, in some embodiments, the proximal end 320 of syringe 300 is sized and adapted for removable insertion into the syringe port of injectors 10, 100 (as shown in FIG1 and FIG3) or for insertion into a pressure sheath (not shown) of a fluid injector. The proximal end 320 of syringe 300 may define an insertion section 330 for removable insertion into the syringe port of injector 10 shown in FIG1 or injector 100 shown in FIG3, while the remainder of syringe 300 remains outside the syringe port. In other embodiments, syringe 300 may be inserted into an inner bore of a pressure sheath and releasably retained in the pressure sheath by one or more retaining features, such as those described in PCT International Application No. PCT / US2020 / 049885, the disclosure of which is incorporated herein by reference. In some embodiments, the proximal end 320 of the syringe 300 includes one or more syringe retaining members 331, which are adapted to form a locking engagement with a corresponding locking mechanism in the syringe port of the injectors 10, 100 to releasably retain the syringe 300 in the syringe port. Suitable non-limiting configurations for releasably locking the syringe 300 and the retaining members of the injectors 10, 100 are described in U.S. Patent Nos. 9,173,995 and 9,199,033, the entire disclosure of which is incorporated herein by reference. For clarity, the syringe 300 is omitted from many figures of the corresponding plunger engagement mechanism of the present invention.

[0206] Referring to Figures 6 through 8C, a plunger 326 according to one embodiment of the present invention is shown. The plunger 326 includes a plunger body 332 defining a plunger longitudinal axis 334 and having a proximal end 336, a distal end 338, and a circumferential sidewall 339 connecting the proximal end 336 and the distal end 338. The sidewall 339 may have a uniform or non-uniform thickness between the proximal end 336 and the distal end 338. At least a portion of the sidewall 339 may be conical. The plunger body 332 may be formed of glass, metal, or a medical-grade plastic.

[0207] The plunger body 332 has an inner cavity 340 (FIG. 7) and a conical portion 342 at its distal end 338 and a cylindrical portion 344 at its proximal end 336. The conical portion 342 may be integrally formed with the cylindrical portion 344. In some embodiments, the conical portion 342 may be attached to or otherwise secured to the cylindrical portion 344 of the plunger body 332 using, for example, a friction fit and / or an adhesive, welding, or molding. The conical portion 342 may have a truncated end 346 having a molded hub 348 configured for engagement with a sensing member, as described herein. In some embodiments, the distal end 338 of the plunger body 332 may be open or closed. In some embodiments, the cylindrical portion 344 may have a protrusion 345 projecting in a radially outward direction relative to the longitudinal axis 334. In this manner, the protruding portion 345 divides the cylindrical portion 344 into a first portion 347a having a first inner diameter and a second portion 347b having a second inner diameter greater than the first inner diameter.

[0208] Referring to Figure 7, the plunger 326 may have one or more release lugs 380 protruding from an inner surface 352 of a cavity 340 of the plunger body 332. In some embodiments, one or more release lugs 380 may protrude radially inward from the inner surface 352 of at least a portion (such as a first portion 347a) of a cylindrical portion 344 of the plunger body 332. One or more release lugs 380 may be configured to interact with at least a portion of a plunger engagement mechanism on the piston to release the plunger 326 from the piston after the plunger 326 has rotated about its longitudinal axis 334 (e.g., by means of a rotary injector 300). In some embodiments, a plurality of release lugs 380 may be radially separated relative to the longitudinal axis 334 of the plunger along a circumference of an inner surface 352 of the cavity 340. In these embodiments, the release lugs 380 are separated from each other by portions of the inner surface 352 of the cavity 340. In embodiments in which more than two release lugs 380 are provided, the release lugs 380 may be evenly spaced from each other. In some embodiments, the release lugs 380 may extend at unequal angles and / or be spaced at unequal angles between the retaining ribs 350 around the inner surface 352 of the cavity 340. One proximal end 382 of each release lug 380 may have a pointed or angled guide surface 384 configured to orient the plunger 326 relative to at least a portion of the plunger engagement mechanism, as described in some embodiments herein.

[0209] Referring to Figure 6, the plunger 326 may have a plunger cap 357 containing a resilient seal 358, which covers at least a portion of an outer surface 360 ​​of the plunger body 332. The seal 358 may be a flexible seal that engages an inner surface 323 of the syringe barrel 318 (as shown in Figure 5B) such that the seal 358 seals the internal volume 325 of the syringe barrel 318 in a liquid-tight manner. The seal 358 may be separate from the plunger body 332, or it may be integrally formed with the plunger body 332, such as by co-molding. In some embodiments, the outer surface 360 ​​of the plunger body 332 may have a circumferential groove 362. At least a portion of the seal 358 may be retained within the circumferential groove 362. The outer surface 364 of the seal 358 may have one or more lips, protrusions, or other sealing elements 366 that slidably engage an inner surface of the syringe barrel 318. In some embodiments, at least the sealing element 366 of the seal 358 may be made of an elastic material that resiliently engages one of the inner surfaces 323 of the syringe barrel 18. At least one extension 356 on the plunger body 332 may prevent the seal 358 from being axially misaligned with the syringe 300 as the plunger 326 moves through the syringe barrel 318.

[0210] Referring to FIG. 7, the plunger 326 may have at least one resiliently deflectable retaining member 368 (hereinafter referred to as "retaining member 368") projecting from the proximal end of the plunger body 332. In some embodiments, the at least one retaining member 368 may project from the proximal end of one inner surface 352 of the cavity 340 of the plunger body 332. The at least one retaining member 368 has a first distal end 370 connected to one of the plunger bodies 332 and a second proximal end 372 that may be radially deflected relative to the first end 370 in a direction toward and / or away from one of the longitudinal axes 334. As described herein, the second end 372 may be radially deflected relative to the first end 370 when the at least one retaining member 368 engages at least a portion of a plunger engagement mechanism on one of the pistons of the injectors 10, 100 (FIGs 1 and 3). That is, as a portion of the plunger engagement mechanism moves in a distal direction and contacts the retaining member 368, the retaining member 368 is radially deflected by the portion of the plunger engagement mechanism. By analogy, during disengagement of the piston from one of the plungers, as a portion of the plunger engagement mechanism moves in a proximal direction and contacts a retaining member 368, the retaining member 368 is radially deflected by that portion of the plunger engagement mechanism. The first end 370 and the second end 372 may be spaced apart in a direction substantially extending along one of the plunger longitudinal axis 334 of the plunger 326. At least one retaining member 368 may be linearly or curvilinearly connected between the first end 370 and the second end 372. In some embodiments, one or more retaining members 368 may extend in a direction parallel to one of the plunger longitudinal axis 334. In other embodiments, one or more retaining members 368 may extend in a direction angled relative to the direction of the plunger longitudinal axis 334. For example, one or more retaining members 368 may be angled toward or away from the plunger longitudinal axis 334 in a direction extending from the proximal end 336 to the distal end 338 of the plunger body 332.

[0211] In some embodiments, a plurality of retaining members 368 are radially spaced apart from the piston longitudinal axis 334 along a circumference of one of the inner surfaces 352 of the cavity 340. In these embodiments, the retaining members 368 are separated from each other by portions of the inner surfaces 352 of the cavity 340. In embodiments where more than two retaining members 368 are provided, the retaining members 368 may be uniformly spaced apart from each other. In an exemplary and non-limiting configuration in which six retaining members 368 have equal angular spacings, such as shown in, for example, Figures 7 through 8C, each retaining member 368 is spaced 60 degrees from adjacent retaining members 368 on both sides. In some embodiments, the retaining members 368 may have unequal angular extensions and / or unequal angular spacings around the inner surface 352 of the cavity 340 among the retaining members 68. The radial spacing of at least one retaining member 368 relative to the piston longitudinal axis 334 is selected to correspond to one of the outer circumferences of the piston, as described herein.

[0212] The second end 372 of the retaining member 368 has at least one detent 374. The at least one detent 374 projects radially from the retaining member 368. The at least one detent 374 is configured to interact with a portion of the plunger engagement mechanism to deflect the second end 372 as the portion of the plunger engagement mechanism passes the at least one detent 374. In some embodiments, the at least one detent 374 may project radially inward toward the plunger longitudinal axis 334 of the plunger body 332. In this manner, the at least one retaining member 368 is configured to deflect in a radially outward direction due to contact between the detent 374 and at least a portion of the plunger engagement mechanism on the piston, as described herein. In some embodiments, the at least one detent 374 may project radially outward away from the plunger longitudinal axis 334 of the plunger body 332. In this manner, the at least one retaining member 368 is configured to deflect in a radially inward direction due to contact between the detent 374 and at least a portion of the plunger engagement mechanism on the piston, as described herein. At least one retaining member 368 is configured to return to its undeflected state by moving in a radially inward direction.

[0213] At least one lever 374 may be integrally formed with the second end 372 of at least one retaining member 368, or may be attached or otherwise secured to the second end 372 of at least one retaining member 368 by, for example, a friction fit and / or an adhesive, welding, or co-molding. In other embodiments, at least one lever 374 may be formed on the second end 372 of at least one retaining member 368 by etching, laser cutting, or machining. As described herein, at least one lever 374 is shaped to be received in a lever receiving space or groove of a plunger engagement mechanism disposed on the piston of injectors 10, 100 to lock at least one retaining member 368 relative to the piston when the plunger engagement mechanism is in a locked state or position by one embodiment of the mechanism described herein. As shown in Figures 7 to 8C, the lever 374 may have a distal surface 377 with a rounded edge. In some embodiments, the lever 374 may have a proximal surface 379 with a rounded edge. The shapes of the distal surface 377 and the proximal surface 379 prevent the lever 374 from engaging with a corresponding locking feature on the piston's plunger engagement mechanism. Instead, the lever 374 must act in conjunction with the actuation of the plunger engagement mechanism to engage with the piston.

[0214] Referring to Figures 8A to 8C, a plunger 326 according to various embodiments of the present invention is shown. The components of the plunger 326 shown in Figures 8A to 8C are substantially similar to or identical to the components of the plunger 326 described herein with reference to Figures 6 and 7. Therefore, the element symbols in Figures 8A to 8C are used to depict the same components as the corresponding element symbols in Figures 6 and 7, and only the relative differences between embodiments of the plunger 326 are discussed herein.

[0215] Referring to Figures 8A to 8C, the plunger 326 may have one or more release lugs 380 protruding from the inner surface 352 of at least a portion (such as the second portion 347b) of the cylindrical portion 344 of the plunger body 332. One or more release lugs 380 may project axially from the protrusion 345 and radially inward from the inner surface 352 of the second portion 347b of the cylindrical portion 344, and may project radially inward from the inner surface 352 of the second portion 347b along the entire width of the protrusion 345 (Figure 8A) or along a portion of the width of the protrusion 345 (Figures 8B and 8C). As described herein, one or more release lugs 380 are configured to interact with at least a portion of the plunger engagement mechanism on the piston to release the plunger 326 from the piston after rotation of the plunger 326 about its longitudinal axis 334 (such as rotation attributable to the syringe 300).

[0216] The embodiment of plunger 326 in Figure 8C has at least one retaining member 368 having a lever 374 that projects radially outward in a direction away from the longitudinal axis 334 of the plunger. In this manner, the at least one retaining member 368 shown in Figure 8C is configured to deflect in a radially inward direction due to contact between the lever 374 and at least a portion of the plunger engagement mechanism on the piston, as described herein. The at least one retaining member 368 shown in Figure 8C is configured to return to its undeflected state by moving in a radially outward direction.

[0217] Referring to Figure 9, one embodiment of a piston 400 detached from an injector is shown. In other embodiments, the piston 400 may be configured for use with a fluid injector such as that described herein or any fluid injector configured for medical use. The piston 400 is configured to reciprocate within the housing of the injector via a drive mechanism. The drive mechanism may include, for example, an electric motor 402 (shown in Figure 2), a hydraulic system, a pneumatic system, or any combination thereof. A controller 200 (Figure 2) may be configured to control the operation of the drive mechanism and, consequently, the reciprocating movement of the piston 400. In some embodiments, the controller 200 may be configured to control the engagement and / or disengagement of the piston 400 from a plunger.

[0218] Referring again to Figure 9, piston 400 has a body 404 and a piston head 406 at a distal end of body 404. Piston head 406 is configured for removable connection to a plunger of a syringe, such as plunger 326 shown in Figure 8C. Piston head 406 extends radially outward beyond the radial edge of body 404. Piston 400 is constructed of a relatively rigid material resistant to deformation (such as metal, plastic, or a combination thereof). Piston head 406 has a substantially cylindrical structure with a distal end configured to be received within at least a portion of the interior of cavity 340 (Figure 8C) of plunger 326. In some embodiments, at least a portion of piston head 406 may be made of a transparent or translucent material configured to allow electromagnetic radiation emitted by one or more electromagnetic radiation sources in piston 400 to pass through and illuminate plunger 326 and / or at least a portion of syringe 300.

[0219] In some embodiments, a sensing member, such as a spring-loaded pin (see, for example, pin 767, Figures 21A-21B), may be provided connected to a sensor. The sensing member may extend along a longitudinal axis of piston 400 and may protrude through at least a portion of piston head 406. The sensing member is operable to sense contact with a surface (such as surface 348 of plunger 326) and control movement of piston 400 based on the sensed conditions. For example, an initial contact between the sensing member and surface 348 of plunger 326 may cause the pin to retract in a proximal direction, thereby contacting the sensor. The sensor may be connected to a drive mechanism of piston 400 such that, after the sensor is actuated by the pin, the sensor controls movement of the drive mechanism. For example, the drive mechanism may stop or slow down from a first rate to a second, slower rate.

[0220] In some embodiments, the piston head 406 has a plunger engagement mechanism 412 configured to releasably engage the plunger 326 to facilitate reciprocating drive of the plunger 326 within the barrel of the syringe 300 (Figures 5A-5B). Continuing to refer to Figure 9, the plunger engagement mechanism 412 has a plunger engagement sleeve 414 including a central opening 416 and a plunger engagement post 418 reciprocating within the central opening 416 of the plunger engagement sleeve 414 along a longitudinal piston axis 420. The plunger engagement post 418 is reciprocated by an actuator 422. The plunger engagement mechanism 412 is operable between an engaged position or state and a disengaged position or state. In the engaged position or state, the plunger engagement post 418 may be positioned within the plunger engagement sleeve 414 to capture at least one retaining member 368 associated with the plunger 326 in a receiving space 415 between the plunger engagement sleeve 414 and the plunger engagement post 418. Conversely, in the disengaged position or state, the plunger engagement post 418 may be positioned relative to the plunger engagement sleeve 414 to allow removal from the receiving space 415 between the plunger engagement sleeve 414 and the plunger engagement post 418 from at least one retaining member 368 associated with the plunger 326. Figure 9 shows portions of the plunger engagement mechanism 412 in the engaged and disengaged positions or states. Specifically, the plunger engagement post 418 in Figure 9 is shown in both its engaged position or state (right side of the cross-section) and its disengaged position or state (left side of the cross-section). During the movement of the plunger engagement mechanism 412 from the engaged position or state to the disengaged position or state, the plunger engagement sleeve 414 and / or the plunger engagement post 418 may move linearly and / or rotationally relative to the piston 400.

[0221] Referring to Figures 10A and 10B, the plunger engagement sleeve 414 has a hollow body 424, wherein at least a portion of the outer surface of one of the hollow body 424 defines at least a portion of the piston head 406 (as shown in Figure 9). A distal portion or distal end 426 of the plunger engagement sleeve 414 is shaped to be received within the cavity 340 of the plunger 326, and at least a portion of the plunger 326 (such as at least one retaining member 368) is configured to be received within a central opening 416 (see, for example, Figure 9). The central opening 416 extends through the hollow body 424 of the plunger engagement sleeve 414.

[0222] Referring to Figure 10B, a portion of the inner surface 428 of the central opening 416 at its distal end may have a bevel 430, such that the inner diameter of the opening 416 narrows in a direction from the distal end 426 of the hollow body 424 toward a proximal portion or proximal end 432. The bevel 430 may be configured to engage with a stop 374 and deflect at least one retaining member 368 associated with the plunger 326 in a radially inward direction during the connection of the plunger 326 to the distal portion or distal end 426 of the plunger engagement sleeve 414. The bevel 430 may terminate at a locking rib 434. Unless the plunger engagement mechanism 412 moves to the locked engagement configuration, at least one stop 374 may be readily flexed and moved via the locking rib 434 as the piston moves in the proximal direction, and flexes against the proximal surface of the locking rib 434. That is, if the piston is in the disengaged configuration, at least one retaining member 368 and the corresponding latch 374 can be easily flexed and moved in and out of the central opening 416 of the plunger engagement sleeve 414. In some embodiments, the locking rib 434 extends continuously or discontinuously around the inner surface 428 of the hollow body 424 of the plunger engagement sleeve 414 and defines one surface of at least one latch 374 on at least one retaining member 368 on the engaging plunger 326 to prevent removal of the plunger 326 from the piston 400 when the plunger 326 is locked engaged with the plunger engagement mechanism 412, as described herein. The inner surface 428 of the central opening 416 may be substantially cylindrical near the proximal end of the locking rib 434.

[0223] One proximal portion or proximal end 432 of the hollow body 424 is integrally formed with the distal portion or distal end 426 and may have an inner surface 436 and a longitudinal groove 438 configured to receive a guide pin 439 of a plunger engagement post 418 (FIG. 9). The longitudinal groove 438 has a distal stop 440 for defining distal movement of the guide pin 439 and thereby defining movement of the plunger engagement post 418 relative to a distal end of the plunger engagement sleeve 414. One outer surface 442 of the proximal portion or proximal end 432 of the hollow body 424 may have a toothed portion 444 configured to interact with one or more release lugs 380 on the plunger 326 during removal of the plunger 326 from the plunger engagement mechanism 412.

[0224] Referring to Figures 11A and 11B, the plunger engagement mechanism 412 further includes a housing 446 configured to receive one of the actuators 422. As shown in Figure 11B, the housing 446 may have a cylindrical structure having a connecting member 448 configured to connect with one of the connectors 450 on the actuator 422. In some embodiments, the connecting member 448 on the housing 446 may be configured to thread-engage one of the internal thread surfaces of an externally threaded connector 450 on the actuator 422. In other embodiments, the connecting member 448 may be an adhesive, a clip, an interference fit, a fastener, or any other connection feature for removably or non-removably connecting the housing 446 to the connector 450 on the actuator 422.

[0225] Referring to Figures 11A and 11B, the housing 446 has a proximal portion 452 connected to a distal portion 454. In some embodiments, the distal portion 454 may have an outer diameter smaller than that of the proximal portion 452, such that a protrusion 456 is defined at a transition between the proximal portion 452 and the distal portion 454. In some embodiments, the protrusion 456 may be configured to support a proximal end of a biasing member 496 configured to release the plunger 326 from the piston engagement mechanism 412 (FIG. 9) during disengagement of the plunger 326 from the piston 400.

[0226] A plunger release sleeve 458 surrounds the distal portion 454 of the housing 446. In some embodiments, the plunger release sleeve 458 has a cylindrical sidewall 460 including an opening 462 extending therethrough. The opening 462 may have a longitudinal surface 463 substantially parallel to a longitudinal axis 464 of the plunger release sleeve 458 and an inclined surface 466 connected to the longitudinal surface 463 and angled downward relative to the longitudinal axis 464 of the plunger release sleeve 458 in a direction from a distal end 468 toward a proximal end 470. As described herein, the longitudinal surface 463 is configured to guide a guide pin 439 of the plunger engagement post 418 (FIG. 9) during movement of the plunger engagement post 418 in a longitudinal direction along a longitudinal axis 420 of the piston 400, while the inclined surface 464 is configured to guide the guide pin 439 during rotational movement of the plunger 326 relative to the piston 400 (such as during removal of the plunger 326 from the piston 400). One or more lamps 472 may be disposed on a printed circuit board 474 connected to the distal end 468 of the plunger release sleeve 458. One or more lamps 472 may be configured to illuminate at least a portion of the plunger 326, as described herein.

[0227] Referring to Figure 11B, actuator 422 can be configured to have an engaged state for moving one of the plunger engagement sleeve 414 and plunger engagement post 418 to an engaged position and a disengaged state for moving one of the plunger engagement sleeve and plunger engagement post to a disengaged position. In some embodiments, actuator 422 can automatically move to the disengaged state, such as during a power outage of actuator 422. In some embodiments, actuator 422 can be in the engaged state only during proximal movement of piston 400. In some embodiments, actuator 422 can be a solenoid configured to be primarily in the disengaged state and can be in the engaged state only during plunger 326 connection to piston 400. In other embodiments, actuator 422 can be a rotary electric motor, a linear electric motor, or a linear actuator. In some embodiments, actuator 422 is a linear actuator that can be manually reverse-driven when the injector is de-energized.

[0228] Referring to Figure 9, the plunger engagement sleeve 414 is rotatable relative to the housing 446 and the plunger release sleeve 458 about the longitudinal piston axis 420 between a first position and a second position. In some embodiments, the plunger engagement sleeve 414 is rotatable in a clockwise and a counterclockwise direction, or in one of a clockwise and a counterclockwise direction. The plunger engagement sleeve 414 can rotate from the first position to the second position due to the rotational movement of the plunger 326 about the longitudinal piston axis 420. For example, the plunger engagement sleeve 414 can rotate about the longitudinal axis 420 due to the interaction between the release lug 380 on the plunger 326 and the toothed portion 444 on the piston engagement sleeve 414. In some embodiments, rotation of the plunger engagement sleeve 414 can move the guide pin 439 along the inclined surface 466 of the plunger release sleeve 458 to move the plunger engagement pin 418 to a disengaged or engaged position. A biasing member 496 may be configured to bias the plunger engagement sleeve 414 to a first position. In this manner, as the plunger engagement sleeve 414 rotates from the first position toward a second position, the biasing member 496 stores potential energy therein, which then assists the plunger engagement sleeve 414 in returning to the first position. In some embodiments, the biasing member 496 may be a torsion spring with one end connected to the plunger engagement sleeve 414 and the other end connected to the housing 446 or the plunger release sleeve 458.

[0229] Referring to Figure 12, a plunger engagement post 418 separated from the plunger engagement mechanism 412 is shown. The plunger engagement post 418 has a shaft 472 comprising a proximal end 474 and a distal end 476. The distal end 476 of the shaft 472 has a tapered end face 478 configured to contact at least one flexible retaining member 368 on the plunger 326 when the plunger engagement post 418 is in an engaged position, so that at least one latch 374 locks the locking rib 434 of the plunger engagement sleeve 414 to prevent the plunger 326 from being removed from the piston 400. A seal 480 may be provided at the distal end 476 to seal the inner surface 428 of the plunger engagement sleeve 414 (as shown in Figures 10A and 10B). The seal 480 may be an O-ring seal.

[0230] The plunger engagement post 418 further includes a guide pin 439 configured to guide movement of the plunger engagement post 418 relative to the plunger engagement sleeve 414. In some embodiments, the guide pin 439 extends through the shaft 472 and is configured substantially perpendicular to one longitudinal axis 482 of the shaft 472. A resilient telescopic member 484 surrounds the shaft 472 and has a distal end 486 adjacent to a projection 488 on the distal end 476 of the shaft 472. A proximal end 490 of the resilient telescopic member 484 may be configured to contact the actuator 422 or the housing 446. The resilient telescopic member 484 may be a compression spring configured to bias the plunger engagement post 418 in a distal direction toward an engaged position, as described herein. In other embodiments, the resilient telescopic member 484 may be a tension spring configured to bias the plunger engagement post 418 in a proximal direction toward a disengaged position.

[0231] After describing the structure of the plunger 326 and piston 400 according to one non-limiting embodiment of the present invention, a method for engaging and disengaging the plunger 326 and piston 400 will now be described with reference to Figures 13A to 13J.

[0232] Figure 13A shows a piston 400 and its plunger engagement mechanism 412 in an engaged position or state before being connected to a plunger 326. In some embodiments, the preset state of the plunger engagement mechanism 412 may be an engaged position or state. To connect the plunger 326 to the piston 400, the syringe 300 is first connected to the injectors 10, 100 (Figures 1 and 3). During the connection of the syringe 300 to the injectors 10, 100, the piston 400 is withdrawn from the housing of the injectors 10, 100. After the syringe 300 is connected to the injectors 10, 100, the piston 400 may advance toward one of the distal ends of the plunger 326.

[0233] Referring to Figure 13B, actuator 422 is energized to retract shaft 472 of plunger engagement post 418 from an engaged position or state to a disengaged position or state in a proximal direction indicated by arrow A. The proximal movement of shaft 472 opens receiving space 415 between plunger engagement sleeve 414 and plunger engagement post 418 to allow insertion or removal of one or more retaining members 368 of plunger 326 into or from the receiving space 415. This movement also compresses a resiliently retractable member 484 between a protrusion 488 on the distal end of shaft 472 and actuator 422. The compression of resiliently retractable member 484 stores potential energy therein, which can be used to guide plunger engagement post 418 toward the engaged position or state upon release.

[0234] In other embodiments, actuator 422 may be de-energized, and the shaft 472 of plunger engagement post 418 may retract from an engaged position or state to a disengaged position or state in a proximal direction indicated by arrow A, due to the elastic restoring force of one of the resilient telescopic members 484. In these embodiments, the resilient telescopic member 484 may be a tension spring that extends from a first state to a second state due to actuation of actuator 422. Once actuator 422 is de-energized, the restoring force of resilient telescopic member 484 propels plunger engagement post 418 toward the disengaged position or state. In this way, plunger engagement post 418 is in a normal disengaged position or state, which allows the plunger 326 to be removed from piston 400 when actuator 422 is inoperable (e.g., due to a power outage).

[0235] Referring to Figure 13C, piston 400 can then be moved axially in a direction toward the distal end of one of the plungers 326 (indicated by arrow B). In some embodiments, piston 400 can be distally advanced using a drive mechanism 402 operated by controller 200 (Figure 2). In other embodiments, piston can be manually moved in the distal direction.

[0236] Referring to Figure 13D, the piston 400 advances axially in a distal direction, such that at least one retaining member 368 of the plunger 326 is received within the central opening 416 of the plunger engagement sleeve 414. Initially, the inner surface 428 of the central opening 416 contacts the latch 374 of the at least one retaining member 368. Because the latch 374 projects radially outward relative to the at least one retaining member 368, the latch 374 is positioned a radial distance further away from the longitudinal axis 334 of the plunger than the ramp 430 of the central opening 416. In this way, continued distal movement of the piston 400 causes the at least one retaining member 368 to deflect radially inward due to contact between the latch 374 and the ramp 430. In embodiments having a plurality of retaining members 368, each of the retaining members 368 deflects in a radially inward direction.

[0237] During the continued axial movement of the piston 400 in a distal direction, the deflector 374 deflects on the locking rib 434 of the piston engagement sleeve 414. After the deflector 374 is positioned proximally relative to the locking rib 434, the distal movement of the piston 400 relative to the plunger 326 stops, or contact between the distal portion of the plunger engagement sleeve 414 or the distal end 426 and the inner surface 352 of the inner cavity 340 of the plunger body 332 causes the plunger 326 to move distally together with the piston 400, and at least one retaining member 368 can be resiliently deflected in a radially inward direction, such that the deflector 374 is positioned proximally to the locking rib 434. In some embodiments, the distal movement of the piston 400 relative to the plunger 326 may stop after a portion of the plunger engagement sleeve 414 engages with the drive shoulder 327 of the plunger 326. When at least one retaining member 368 is in the position shown in FIG. 13D, the plunger 326 is not locked into engagement with the piston 400 because at least one retaining member 368 can deflect in a radially inward direction as the proximal end of the piston 400 moves or the distal end of the plunger 326 moves (e.g., due to syringe removal from the injector). When the plunger 326 is engaged with the piston 400, one or more release lugs 380 on the plunger 326 align with a toothed portion 444 on the outer surface 442 of the plunger engagement sleeve 414. In some embodiments, the plunger 326 may not be in an engaged, locked position with one of the pistons 400 as the piston 400 moves in a distal direction and may only move to the engaged, locked position after the proximal end of the piston 400 has moved. This feature allows for easy removal of the syringe 300 and the plunger 326 after a short distal movement of one of the pistons 400 and reduces wear on system components and / or the motor by requiring only a locking engagement when the piston 400 retracts.

[0238] Referring to Figure 13E, actuator 422 is de-energized to allow the shaft 472 of plunger engagement post 418 to move from a disengaged position or state to an engaged position or state in a distal direction indicated by arrow C. In other embodiments, actuator 422 may be energized to move the shaft 472 of plunger engagement post 418 in a distal direction.

[0239] Movement of shaft 472 in the distal direction closes the receiving space 415 between plunger engagement sleeve 414 and plunger engagement post 418, causing at least one latch 374 to lock the locking rib 434 to prevent removal of one or more retaining members 368 of plunger 326 from the receiving space 415, thus preventing removal of plunger 326 from piston 400. The plunger engagement post 418 moves from a disengaged position or state to an engaged position or state due to the release of potential energy stored in the resiliently retractable member 484. In other embodiments, the plunger engagement post 418 moves from a disengaged position or state to an engaged position or state due to actuation of actuator 422, where potential energy is stored in the resiliently retractable member 484. Once the plunger engagement post 418 has moved to the engaged position or state, at least one retaining member 368 of plunger 326 is engaged between plunger engagement sleeve 414 and plunger engagement post 418, such that axial movement of piston 400 causes corresponding axial movement of plunger 326 within syringe barrel. Next, the piston 400 and the connecting plunger 326 can reciprocate within the barrel 318 of the syringe 300 (Figures 5A to 5B). In a particular embodiment, the piston 400 and the connecting plunger 326 can move proximally within the barrel 318 and distally when the piston 400 and the plunger 326 are in an engaged or disengaged position. In some embodiments, the piston 400 can advance distally to deliver fluid from the syringe 300 or proximally to fill the syringe 300 with fluid using a drive mechanism 402 operated by the controller 200 (Figure 2).

[0240] In some embodiments involving manual disengagement of the syringe, to unlock the syringe 300 from the syringe port of the injector and disengage the plunger 326 from the piston 400, the syringe 300 can be rotated clockwise or counterclockwise relative to the syringe port about the longitudinal axis of the syringe. Since the plunger 326 does not rotate substantially due to frictional interaction with the syringe barrel 318, rotation of the syringe 300 also causes the plunger 326 to rotate relative to the piston 400 about the longitudinal piston axis 420. Rotation of the plunger 326 also causes the plunger engagement sleeve 414 to rotate from a first position to a second position relative to the plunger release sleeve 458 of the plunger engagement mechanism 412, due to the alignment of one or more release lugs 380 on the plunger 326 with the toothed portion 444 on the outer surface 442 of the plunger engagement sleeve 414. Because the guide pin 439 on the plunger engagement post 418 is received within a longitudinal groove 438 of the plunger engagement sleeve 414, the plunger engagement post 418 also rotates with the plunger engagement sleeve 414. The rotation of the plunger engagement post 418 causes the guide pin 439 to be guided along the inclined surface 466 of the plunger release sleeve 458 (see Figure 13F) and compress the elastically retractable member 484. Additionally, the rotation of the plunger engagement sleeve 414 about the longitudinal piston axis 420 accumulates potential energy in the biasing member 496.

[0241] In other embodiments (such as when the syringe is housed within a pressure sheath), the syringe and plunger cannot be rotated to disengage the plunger 326 from the piston 400. According to these embodiments, the disengagement and engagement of the piston 400 and plunger 326 can be performed electromechanically, for example by using a motorized or electric actuator to disengage the plunger 326 from the piston 400. As described herein, a motor (such as a linear or rotary electric motor) or an electric actuator (such as a solenoid) can be used to move the plunger engagement post 418 between an engaged position and a disengaged position to engage and disengage the plunger 326 from the piston 400. When the plunger 326 is in the disengaged position (such as at the end of an injection procedure), the syringe 300 can be removed from the injector, and the injector is ready for the next procedure.

[0242] Referring to Figure 13G, movement of the guide pin 439 along the inclined surface 466 of the plunger release sleeve 458 causes the plunger engagement pin 418 to move axially from an engaged position or state to a disengaged position or state in the proximal direction of one of the arrows D. In some embodiments, the plunger engagement pin 418 can be moved proximally by energizing the actuator 422 to retract the shaft 472 of the plunger engagement pin 418. In this way, the plunger engagement pin 418 can be moved manually, such as by rotation of the plunger 326 relative to the piston 400 or by actuation of the actuator 422. Thus, in the event of a power outage, the plunger 326 can be removed from the piston 400. The proximal movement of the plunger engagement pin 418 opens a receiving space 415 between the plunger engagement sleeve 414 and the plunger engagement pin 418 to allow one or more retaining members 368 of the plunger 326 to be removed from the receiving space 415. Furthermore, this configuration, in which only the actuator 422 needs to be engaged, can reduce wear on system components and / or the motor by requiring only a locking engagement when the piston 400 moves in a proximal direction.

[0243] When the plunger engagement mechanism 412 is in the disengaged position or state, the syringe 300 can be pulled in the distal direction or the piston 400 can be retracted in the proximal direction to remove the plunger 326 from the piston 400 and remove the syringe 300 and plunger 326 from the fluid injector. During the relative movement of the pistons 400 toward the plunger 326 in one of the directions away from each other, the latch 374 deflects on the locking rib 434 of the piston engagement sleeve 414 to allow removal of one or more retaining members 368 from the piston 400. Subsequently, the plunger 326 can be freely pulled away from the piston 400, as shown in Figure 13H.

[0244] Referring to Figures 13I to 13J, after the plunger 326 is removed from the piston 400, the plunger engagement sleeve 414 and the plunger engagement pin 418 automatically rotate from a second position to a first position about the longitudinal piston axis 420 (as shown in Figure 9) due to the restoring force provided by the biasing member 496. As the plunger engagement sleeve 414 and the plunger engagement pin 418 move to the first position, the guide pin 439 is guided along the inclined surface 466 of the plunger release sleeve 458 toward one of its distal ends due to the restoring force provided by the resilient telescopic member 484. This causes the plunger engagement pin 418 to move in the direction of one of the distal ends of arrow E. The position of the plunger engagement mechanism 412 in Figure 13J is the same as the position of the plunger engagement mechanism 412 in Figure 13A.

[0245] Referring to Figures 14A to 14C, a piston 500 and a plunger engagement mechanism 512 according to another embodiment of the present invention are shown. The components of the piston 500 and plunger engagement mechanism 512 shown in Figures 14A to 14C are substantially similar to or identical to the components of the piston 400 and plunger engagement mechanism 412 described herein with reference to Figures 9 to 13J. Therefore, except that the first digit of the component symbols used in Figures 14A to 14C has changed from "4" to "5", the component symbols in Figures 14A to 14C are used to depict the same components as the corresponding component symbols in Figures 9 to 13J. For example, a piston described in conjunction with Figures 9 to 13J is identified by a component symbol "400", while the pistons in Figures 14A to 14C are identified by a component symbol "500". Since the previous discussion regarding the piston 400 and plunger engagement mechanism 412 generally shown in Figures 9 to 13J is applicable to the piston 500 and plunger engagement mechanism 512 shown in Figures 14A to 14C, the following discussion will only focus on the relative differences between the components shown in these figures.

[0246] The piston 400 and plunger engagement mechanism 412 shown in Figures 9 to 13J are configured to interact with one of the plungers 326 shown in Figures 6 to 8B, while the piston 500 and plunger engagement mechanism 512 of Figures 14A to 14C are configured to interact with the plunger 326 of Figure 8C. In this manner, at least one retaining member 368 shown in Figures 6 to 8B is configured to deflect in a radially outward direction due to contact between the stop 374 and at least a portion of the plunger engagement mechanism 512 on the piston, as described herein. At least one retaining member 368 shown in Figures 6 to 8B is configured to return to its undeflected state by moving in a radially inward direction.

[0247] Referring again to FIG. 14A, the plunger engagement mechanism 512 has a plunger engagement sleeve 514 with a central opening 516 and a plunger engagement post 518. The plunger engagement post 518 has a proximal portion 519 rotatably connected to the plunger release sleeve 558, such that the plunger engagement post 518 can rotate about a longitudinal piston axis 520. Referring to FIG. 15, the proximal portion 519 may have a toothed portion 544 at its distal end. As with the toothed portion 444 of the plunger engagement mechanism 412 described herein with reference to FIGS. 9 to 13J, the toothed portion 544 is configured to interact with a release lug 380 on the plunger 326 (FIGs 8A, 8B, and 14A). The plunger engagement post 518 further has a post portion 521 extending from the distal end of the proximal portion 519. In some embodiments, the proximal portion 519 and the post portion 521 may be integrally formed to constitute a single integral part. One or more openings 523 may be formed in a plunger engagement post 518 via a connector 525 connecting the proximal portion 519 to one of the post portions 521. The openings 523 may be configured to pass through a portion of their receiving plunger engagement sleeve 514. An upper surface of the connector 525 defines an engagement surface for contacting at least a portion of the plunger 326 (such as a drive shoulder 327 of the plunger 326). The plunger engagement post 518 further has a longitudinal groove 538 configured to receive a guide pin 539. The longitudinal groove 538 has a distal stop 540 for defining distal movement of the guide pin 539 and thereby defining distal movement of the plunger engagement sleeve 514 relative to the distal end of the plunger engagement post 518.

[0248] The plunger engagement post 518 in Figures 14A to 14C is rotatable only about the piston longitudinal axis 520. The plunger engagement post 518 is rotatable about the longitudinal piston axis 520 and the plunger release sleeve 558 between a first position and a second position. In some embodiments, the plunger engagement post 518 is rotatable in a clockwise and a counterclockwise direction, or in one of a clockwise and a counterclockwise direction. The plunger engagement post 518 may be rotated from the first position to the second position due to the rotational movement of the plunger 326 about the longitudinal piston axis 520. For example, the plunger engagement post 518 may be rotated about the longitudinal axis 520 due to the interaction between the release lug 380 on the plunger 326 and the toothed portion 544 on the piston engagement post 518. A biasing member (not shown) (similar to the biasing member 496 shown in Figure 9) may be configured to bias the plunger engagement post 518 to the first position. In this manner, as the plunger engagement post 518 rotates from the first position toward the second position, a biasing member stores potential energy therein, which then assists the plunger engagement post 518 in returning to the first position. In some embodiments, the biasing member may be a torsion spring with one end connected to the plunger engagement post 518 and the other end connected to the plunger release sleeve 558.

[0249] Referring again to Figure 15, the pillar portion 521 of the plunger engagement pillar 518 has a locking groove 527 of a latch 374 configured to receive at least one flexible retaining member 368 of the plunger 326. The distal end of the pillar portion 521 may be shaped to deflect at least one retaining member 368 in a radially outward direction due to contact between the latch 374 and an outer surface of the pillar portion 521. In some embodiments, the distal end of the pillar portion 521 may include a ramp to further deflect at least one retaining member 368 in a radially outward direction. In this way, movement of the piston 500 relative to the distal end of the plunger 326 causes at least one retaining member 368 to deflect radially outward due to contact between the latch 374 and the outer surface of the pillar portion 521. In embodiments having a plurality of retaining members 368, each of the retaining members 368 deflects radially outward.

[0250] Referring to Figure 14A, a plunger release sleeve 558 is at least partially received within the hollow structure of a plunger engagement sleeve 514 and a plunger engagement post 518. Referring to Figure 16, the plunger release sleeve 558 has a cylindrical sidewall 560 with an opening 562 extending therethrough. The opening 562 may have a longitudinal surface 563 substantially parallel to a longitudinal axis 564 of the plunger release sleeve 558 and an inclined surface 566 connected to the longitudinal surface 563 and angled downward relative to the longitudinal axis 564 of the plunger release sleeve 558 in a direction from a distal end 568 toward a proximal end 570. As described herein, longitudinal surface 563 is configured to guide guide pin 539 (FIG. 14A) during the movement of plunger engagement sleeve 514 in one of the longitudinal directions along the longitudinal axis 520 of piston 500, while inclined surface 564 is configured to guide guide pin 539 during rotational movement of plunger 326 relative to piston 500 (or vice versa) such as during removal of plunger 326 from piston 500.

[0251] Referring to Figures 17A and 17B, a plunger engagement sleeve 514, separated from the remainder of the plunger engagement mechanism 512, is shown. The plunger engagement sleeve 514 has a hollow body 524, at least a portion of which is configured to be received within the proximal portion 519 of the plunger engagement post 518. A distal portion or distal end 526 of the plunger engagement sleeve 514 is shaped to be received through an opening 523 on the plunger engagement post 518 (Figure 15) and positioned within the cavity 340 of the plunger 326 (Figures 14A and 14B). At least a portion of the plunger 326 (such as at least one retaining member 368) is configured to be received within a central opening 516 and in a receiving space 515 between the post portion 521 of the plunger engagement post 518 and the distal portion or distal end 526 of the plunger engagement sleeve 514. A portion of the inner surface 528 of one of the central openings 516 may have a bevel 530, such that the inner diameter of one of the openings 516 narrows in a direction from the distal end 526 of the hollow body toward a proximal portion or proximal end 532. The bevel 530 may be configured to deflect at least one retaining member 368 associated with the plunger 326 in a radially inward direction during the connection of the plunger 326 to the piston 500 and to create a tight engagement interaction between the latch 374 of the at least one flexible retaining member 368 and the locking groove 527 of the plunger engagement post 518.

[0252] Referring again to Figures 17A and 17B, the hollow body 524 of the plunger engagement sleeve 514 has a through-hole 533 configured for receiving the guide pin 539. The plunger engagement sleeve 514 is configured to rotate about its longitudinal axis 531 due to engagement between the guide pin 539 and the inclined surface 566 of the plunger release sleeve 558 (due to the rotation of the plunger 326 and the plunger engagement post 518).

[0253] After describing the structure of the plunger 326 and piston 500 according to one non-limiting embodiment of the present invention, a method for engaging and disengaging the plunger 326 and piston 500 will now be described with reference to Figures 14A to 14C.

[0254] Figure 14B shows the piston 500 and its plunger engagement mechanism 512 in a disengaged position or state before locking engagement with the plunger 326. In Figure 14B, the piston 500 has advanced toward one of the distal ends of the plunger 326. In some embodiments, the piston 500 may be advanced distally using a drive mechanism 402 operated by the controller 200 (Figure 2). In other embodiments, the piston may be moved manually in the distal direction.

[0255] Referring again to FIG14B, the latch 374 on at least one retaining member 368 of plunger 326 deflects in a radially outward direction due to contact with the outer surface of the plunger portion 521. After the latch 374 is positioned within the locking groove 527 (such as when the upper surface of connector 525 engages the drive shoulder 327 of plunger 326), the piston 500 stops moving relative to the distal end of plunger 326 and at least one retaining member 368 can be resiliently deflected in a radially inward direction, such that the latch 374 is positioned within the locking groove 527. When at least one retaining member 368 is in the position shown in FIG14B, plunger 326 is not locked into engagement with piston 500 because, due to the flexibility of the material between the first distal end 370 and a second proximal end 372 (see FIG7), at least one retaining member 368 can deflect in a radially outward direction as the proximal end of piston 500 moves or the distal end of plunger 326 moves (such as due to self-injector removal of the syringe). As shown in Figure 14B, when the plunger 326 contacts the piston 500, one or more release lugs 380 on the plunger 326 are aligned with the toothed portion 544 on the plunger engagement post 518.

[0256] Referring to Figures 14A and 14C, the plunger engagement sleeve 514 moves from a disengaged position or state to an engaged position or state. This movement of the plunger engagement sleeve 514 can be attributed to de-energizing the actuator and allowing a resiliently retractable member (such as the resiliently retractable member 484 described herein with reference to Figures 9 to 13J) to axially advance the plunger engagement sleeve 514 in a distal direction. In other embodiments, this movement of the plunger engagement sleeve 514 can be attributed to energizing the actuator to axially advance the plunger engagement sleeve 514 in a distal direction. For example, the actuator may be actuated by a rotary or linear motor to move the actuator from a disengaged position to an engaged position in a distal direction. Energizing the actuator in this way causes the plunger engagement sleeve 514 to move in the distal direction and accumulates a resilient restoring force in the resiliently retractable member. The distal movement of the plunger engagement sleeve 514 closes the receiving space 515 between the plunger engagement sleeve 514 and the plunger engagement post 518 to prevent one or more retaining members 368 of the plunger 326 from being removed from the receiving space 515 and from the latches 374 and locking grooves 527 of the one or more flexible retaining members 368. Once the plunger engagement sleeve 514 is moved to the engaged position or state, at least one retaining member 368 of the plunger 326 is engaged between the plunger engagement sleeve 514 and the plunger engagement post 518, such that axial movement of the proximal end of the piston 500 causes corresponding axial movement of the plunger 326 within the syringe barrel. Subsequently, the piston 500 and the connecting plunger 326 can reciprocate within the barrel 318 of the syringe 300.

[0257] To unlock the syringe 300 from the syringe port of the injector and disengage the plunger 326 from the piston 500, the syringe 300 rotates clockwise or counterclockwise relative to the syringe port about the longitudinal axis of the syringe. Since the plunger 326 does not actually rotate within the syringe barrel 318 due to friction, the rotation of the syringe 300 also causes the plunger 326 to rotate relative to the piston 500 about the longitudinal piston axis 520. Due to the alignment of one or more release lugs 380 on the plunger 326 with the toothed portion 544 on the plunger engagement post 518, the rotation of the plunger 326 also causes the plunger engagement post 518 to rotate from a first position to a second position relative to the plunger release sleeve 558. Because the guide pin 539 on the plunger engagement sleeve 514 is received within a longitudinal groove 538 of the plunger engagement post 518, the plunger engagement sleeve 514 also rotates with the plunger engagement post 518. Rotation of the plunger engagement sleeve 514 causes the guide pin 539 to be guided along the inclined surface 566 of the plunger release sleeve 558 (see Figure 16) to move the plunger engagement sleeve 514 in a proximal direction and compress the elastic retractable member in a manner similar to the operation of the resilient retractable member 484 described herein with reference to Figures 9 to 13J. Additionally, rotation of the plunger engagement pin 518 about the longitudinal piston axis 520 can accumulate potential energy in the biasing member in a manner similar to the operation of the biasing member 496 described herein with reference to Figures 9 to 13J.

[0258] Movement of the guide pin 539 along the inclined surface 566 of the plunger release sleeve 558 causes the plunger engagement sleeve 514 to move axially in a proximal direction from the engaged position or state to the disengaged position or state shown in FIG. 14A. In some embodiments, the plunger engagement sleeve 514 can be moved in the proximal direction by energizing or de-energizing the actuator to retract it. The proximal movement of the plunger engagement sleeve 514 opens the receiving space 515 between the plunger engagement sleeve 514 and the plunger engagement pin 518 to allow removal of the latches 374 and locking grooves 527 of one or more flexible retaining members 368 and to allow removal of one or more retaining members 368 of the plunger 326 from the receiving space 515.

[0259] Referring to Figures 18A and 18B, a piston 600 and a plunger engagement mechanism 612 according to another embodiment of the present invention are shown. The components of the piston 600 and plunger engagement mechanism 612 shown in Figures 18A and 18B are substantially similar to or identical to the components of the piston 400 and plunger engagement mechanism 412 described herein with reference to Figures 9 to 13J. Therefore, except that the first digit of the component symbols used in Figures 18A and 18B has changed from "4" to "6", the component symbols in Figures 18A and 18B are used to depict the same components as the corresponding component symbols in Figures 9 to 13J. For example, a piston described in conjunction with Figures 9 to 13J is identified by a component symbol "400", while the piston in Figures 18A and 18B is identified by a component symbol "600". Since the previous discussion regarding the piston 400 and plunger engagement mechanism 412 generally shown in Figures 9 to 13J is applicable to the piston 600 and plunger engagement mechanism 612 shown in Figures 18A to 18B, the following discussion will only focus on the relative differences between the components shown in these figures.

[0260] Referring to FIG18A, the plunger engagement mechanism 612 has a plunger engagement sleeve 614 having a central opening 616 and a plunger engagement post 618 reciprocating within the central opening 616 of the plunger engagement sleeve 614 in one direction of a longitudinal piston axis 620. The plunger engagement post 618 is reciprocatedly driven by an actuator (such as actuator 422 shown herein with reference to FIG9). In some embodiments, the actuator may be a solenoid configured to be primarily in a disengaged state and may be in an engaged state only during the engagement of the plunger 326 with the piston. In other embodiments, the actuator may be a rotary electric motor, a linear electric motor, or a linear actuator. In some embodiments, the actuator is a linear actuator that can be manually reversed when the injector is de-energized.

[0261] The plunger engagement mechanism 612 is operable between an engaged position or state and a disengaged position or state. In the engaged position or state, the plunger engagement post 618 may be positioned within the plunger engagement sleeve 614 to capture at least one retaining member 368 associated with the plunger 326 in a receiving space 615 between the plunger engagement sleeve 614 and the plunger engagement post 618. Conversely, in the disengaged position or state, the plunger engagement post 618 may be positioned proximal to the plunger engagement sleeve 614 to allow removal of at least one retaining member 368 associated with the plunger 326 from the receiving space 615 between the plunger engagement sleeve 614 and the plunger engagement post 618.

[0262] Referring again to Figure 18A, the plunger engagement sleeve 614 has a hollow body 624, wherein at least a portion of the outer surface of the hollow body 624 defines at least a portion of the piston head 606. A distal portion or distal end 626 of the plunger engagement sleeve 614 is shaped to be received within the cavity 340 of the plunger 326, and at least a portion of the plunger 326 (such as at least one retaining member 368) is configured to be received within a central opening 616. The central opening 616 extends through the hollow body 624 of the plunger engagement sleeve 614. An inner surface of the central opening 616 may have a chamfer 630 such that an inner diameter of the opening 616 narrows in a direction from the distal end of the hollow body 624 toward a proximal portion or proximal end. The ramp 630 may be configured to deflect at least one retaining member 368 associated with the plunger 326 in a radially inward direction by contacting a latch 374 of one or more flexible retaining members 368 during the movement of the piston head 606 relative to the distal end of the plunger 326 with the plunger engaging sleeve 614. The ramp 630 may terminate at a locking rib 634. One outer surface 642 of the plunger engaging sleeve 614 may have a toothed portion 644 similar to the toothed portion 444 described herein with reference to Figures 9 to 13J. The toothed portion 644 may be configured to interact with one or more release lugs 380 on the plunger 326 during rotation of the plunger 326 relative to the piston 600 (as shown in Figure 8C).

[0263] Referring to Figure 18B, a plunger engagement post 618 separated from the plunger engagement mechanism 612 is shown. The plunger engagement post 618 has a shaft 672 comprising a proximal end 674 and a distal end 676. The distal end 676 of the shaft 672 has a tapered end face 678 configured to contact at least one retaining member 368 on the plunger 326 when the plunger engagement post 618 is in an engaged position to prevent the plunger 326 from being removed from the piston 600. The proximal end 674 of the shaft 672 is configured to connect to an actuator (similar to the actuator 422 described herein with reference to Figures 9 through 13J) to move the plunger engagement post 618 relative to the plunger engagement sleeve 614 between an engaged position or state and a disengaged position or state.

[0264] Referring again to FIG18B, the plunger engagement post 618 further includes at least one groove 665 recessed at its distal end 676 into the body of the shaft 672. In some embodiments, the at least one groove 665 may be configured to receive at least one retaining member 368 of the plunger 326 when the plunger engagement post 618 rotates about a longitudinal axis 667. The at least one groove 665 may be linearly or curvilinearly connected between a protrusion 679 near the proximal end 674 and the distal end 676 of the shaft 672. In some embodiments, the at least one groove 665 may extend in a direction parallel to one of the longitudinal axes 667 of the plunger engagement post 618.

[0265] Referring again to FIG18B, a plurality of grooves 665 are radially spaced apart from the longitudinal axis 667 along a circumference of the distal end 676 of the shaft 672. In embodiments in which more than two grooves 665 are provided, the grooves 665 may be evenly spaced apart from each other and separated from each other by an outer surface 667 of the shaft 672. In some embodiments, the number and spacing of the grooves 665 may correspond to the number and spacing of the retaining members 368 on the plunger 326. In an exemplary and non-limiting configuration in which the six retaining members 368 are spaced at equal angles, such as as shown in FIG8C, the corresponding plunger engagement post 618 has six grooves 665 spaced 60 degrees from the adjacent grooves 665 on both sides.

[0266] Referring to FIG18A, the proximal end 674 of shaft 672 is received within a rotating mechanism 671, which is slidably mounted within the hollow body 624 of plunger engagement sleeve 614. In some embodiments, the rotating mechanism 671 may have a first portion 673 slidably mounted within the hollow body 624 and fixed relative to the plunger engagement sleeve 614 without rotation, and a second portion 675 fixed to the plunger engagement post 618 and rotatable relative to the first portion 673 and the plunger engagement sleeve 614. In some embodiments, the rotating mechanism 671 may be configured for unidirectional rotation, such as in a clockwise or counterclockwise direction about a longitudinal axis 620. For example, the rotating mechanism 671 may be a one-way clutch.

[0267] After describing the structure of the plunger 326 and piston 600 according to one non-limiting embodiment of the present invention, a method for engaging and disengaging the plunger 326 and piston 600 will now be described.

[0268] Figure 18A shows the piston 600 and its plunger engagement mechanism 612 in an engaged position or state with one of the plungers 326. As described herein with reference to Figures 13A to 13J, the plunger 326 can be connected to the piston 600 by distally moving the piston 600 to allow one or more retaining members 368 of the plunger 326 to be inserted into the receiving space 615 between the plunger engagement sleeve 614 and the plunger engagement post 618. In some embodiments, the piston 600 can be distally advanced using a drive mechanism 402 operated by the controller 200 (Figure 2). In other embodiments, the piston 600 can be manually moved in the distal direction.

[0269] The piston 600 advances axially in a distal direction, causing at least one retaining member 368 of the plunger 326 to be flexibly received within the central opening 616 of the plunger engagement sleeve 614, such that at least one retaining member 368 is radially inwardly deflected due to contact between the latch 374 and the ramp 630. In embodiments having a plurality of retaining members 368, each of the retaining members 368 is deflected in a radially inward direction. In some embodiments, a guide surface may be present on the side of the tapered end face 678 to assist the plunger engagement post 618 in rotating into the correct orientation for self-alignment with the retaining member 368 on the plunger 326.

[0270] During the continued axial movement of piston 600 in a distal direction, latch 374 is radially inwardly deflected on locking rib 634 of piston engagement sleeve 614. After latch 374 is positioned proximally relative to locking rib 634, movement of piston 600 relative to the distal end of plunger 326 ceases (e.g., when drive shoulder 327 of plunger 326 engages one corresponding drive protrusion 637 on piston 600), and at least one retaining member 368 is resiliently deflected in a radially outward direction, such that latch 374 is positioned proximally to locking rib 634. In this configuration, plunger engagement post 618 remains in a disengaged position or state, such as due to actuation of the actuator described herein with reference to Figures 9 through 14C. When plunger 326 is engaged with piston 600, one or more release lugs 380 on plunger 326 align with toothed portions 644 on outer surface 642 of plunger engagement sleeve 614.

[0271] As the plunger engagement post 618 moves distally from the disengaged state or position to the engaged state or position, the receiving space 615 between the plunger engagement sleeve 614 and the plunger engagement post 618 closes to prevent one or more retaining members 368 of the plungers 326 from being removed from the receiving space 615. As the plunger engagement post 618 moves to the engaged position or position, a latch 374 of at least one retaining member 368 of the plungers 326 engages between the plunger engagement sleeve 614 and the outer surface 667 of the plunger engagement post 618 near the locking rib 634. The piston 600 and the connecting plunger 326 can then reciprocate within the barrel 318 of the syringe 300. In some embodiments, the piston 600 can advance distally to deliver fluid from the syringe 300 or proximally to fill the syringe 300 with fluid using a drive mechanism 402 operated by the controller 200 (FIG. 2).

[0272] To unlock the syringe 300 from the syringe port of the injector and disengage the plunger 326 from the piston 600, the syringe 300 can rotate clockwise or counterclockwise relative to the syringe port about its longitudinal axis. Rotation of the plunger 326 also causes the plunger engagement sleeve to rotate because one or more release lugs 380 on the plunger 326 align with the toothed portion 644 on the plunger engagement sleeve 614. Since the plunger engagement post 618 is connected to the plunger engagement sleeve 614 via a rotating mechanism 671, the plunger engagement post 618 does not rotate with the plunger engagement sleeve 614. In this manner, the retaining member 368 of the plunger 326 slides into the groove 665 on the plunger engagement post 618.

[0273] When the retaining member 368 of the plunger 326 is positioned in the groove 665 of the plunger engagement post 618, the receiving space 615 between the plunger engagement sleeve 614 and the plunger engagement post 618 opens to allow one or more retaining members 368 of the plunger 326 to be removed from the receiving space 615 by distal movement of a lever 374 that flexes at least one retaining member 368 on the locking rib 634. The syringe 300 may be pulled in the distal direction or the plunger 326 may be retracted in the proximal direction to remove the plunger 326 from the piston 600. During relative movement of the pistons 600 toward the plunger 326 in a direction away from each other, the lever 374 deflects on the locking rib 634 of the piston engagement sleeve 614 to allow removal of one or more retaining members 368 from the piston 600.

[0274] Referring to Figures 19 to 21B, a piston 700 and a plunger engagement mechanism 712 according to another embodiment of the present invention are shown. The components of the piston 700 and plunger engagement mechanism 712 shown in Figures 19 to 21B are substantially similar to or identical to the components of the piston 400 and plunger engagement mechanism 412 described herein with reference to Figures 9 to 13J. Therefore, except that the first digit of the component symbols used in Figures 19 to 21B has changed from "4" to "7", the component symbols in Figures 19 to 21B are used to depict the same components as the corresponding component symbols in Figures 9 to 13J. Since the previous discussion regarding the piston 400 and plunger engagement mechanism 412 generally shown in Figures 9 to 13J is applicable to the piston 700 and plunger engagement mechanism 712 shown in Figures 19 to 21B, the following discussion will only focus on the relative differences between the components shown in these figures.

[0275] Referring first to Figure 19, a piston 700 and plunger engagement mechanism 712 are shown in combination with a syringe port 16 of an injector (such as injector 10 shown in Figure 1). The piston 700 can reciprocate within the syringe port 16 in one direction of a longitudinal piston axis 720, such as via a drive mechanism 402 shown in Figure 2.

[0276] Referring to Figure 20, an exploded view of a piston 700 and a plunger engagement mechanism 712 is shown. The piston 700 has a body 704 and a piston head 706 at a distal end of the body 704. The piston head 706 is configured for removable connection to a plunger of a syringe, such as the plunger 326 shown in Figures 7-8B. The plunger engagement mechanism 712 is integrated into the piston head 706. In some embodiments, at least a portion of the piston head 706 and / or the plunger engagement mechanism 712 may be made of a transparent or translucent material configured to allow light emitted by one or more lamps in the piston 700 to pass through and illuminate the plunger 326 and / or at least a portion of the syringe 300.

[0277] Referring again to FIG. 20, piston 700 has a sensing element 705, such as a pin 707 and a sensor 709. Pin 707 has a proximal end 713 configured to contact sensor 709 (e.g., due to contact between plunger 326 and the distal end 715 of pin 707) when one distal end 715 of pin 707 is advanced in a proximal direction. Pin 707 may extend along a longitudinal axis 720 of piston 700 and may protrude through at least a portion of piston head 706. Pin 707 is operable to sense contact with a surface (such as one surface of plunger 326) and send one or more signals to controller 200 (FIG. 2) to control movement of piston 700 based on sensing conditions. For example, an initial contact between the distal end 715 of pin 707 and plunger 326 may cause pin 707 to move in a proximal direction, causing it to contact sensor 709. Sensor 709 is operatively connected to controller 200 such that, after sensor 709 is actuated by pin 707, sensor 709 controls the movement of the drive mechanism of piston 700. For example, the drive mechanism can be stopped or slowed from a first rate to a second slower rate and the distal end 715 of pin 707 and plunger 326 can be stopped. Pin 707 can be biased to its distal position by a spring 711.

[0278] Referring again to FIG. 20, the plunger engagement mechanism 712 has a plunger engagement sleeve 714 with a central opening 716 and a plunger engagement post 718. Due to the activation of an actuator 722 (shown in FIG. 21A-21B), the plunger engagement post 718 is translatable relative to the plunger engagement sleeve 714 along the longitudinal piston axis 720. In some embodiments, the plunger engagement post 718 is axially movable between an engagement position in which the plunger 326 is locked into engagement with the piston 700 due to at least one retaining member 368 of the plunger 326 being captured between the plunger engagement sleeve 714 and the plunger engagement post 718, and a disengagement position in which the plunger 326 is removable from the piston 700.

[0279] Referring again to Figure 20, the plunger engagement post 718 has a post portion 721 extending distally from a proximal portion 723. The plunger engagement post 718 further has a radial groove 737 configured to receive a guide pin (not shown). The post portion 721 of the plunger engagement post 718 has a locking lip 729 configured to interact with a latch 374 of at least one retaining member 368 of the plunger 326. The post portion 721 may be shaped to deflect at least one retaining member 368 in a radially outward direction due to contact between the latch 374 and an outer surface of the post portion 721 and / or the locking lip 729. In this way, movement of the piston 700 relative to the distal end of the plunger 326 causes at least one retaining member 368 to deflect radially outward due to contact between the latch 374 and the post portion 721. In embodiments having a plurality of retaining members 368, each of the retaining members 368 deflects radially outward.

[0280] Referring again to Figure 20, the plunger engagement sleeve 714 has a hollow body 724, wherein at least a portion of the outer surface of one of the hollow bodies 724 defines at least a portion of the piston head 706. A distal portion or distal end 726 of the plunger engagement sleeve 714 is shaped to be received within the cavity 340 of the plunger 326 (as shown in Figure 21A), and at least a portion of the plunger 326 (such as at least one retaining member 368) is configured to be received within a central opening 716. The central opening 716 extends through the hollow body 724 of the plunger engagement sleeve 714.

[0281] A portion of the inner surface 728 of the central opening 716 at its distal end may have a stepped inner diameter that decreases in diameter in a direction from the distal end of the plunger engagement sleeve 714 to the proximal end of the plunger engagement sleeve 714. For example, the opening 716 may have a first step 717 having a first inner diameter and a second step 719 located proximal to the first step 717 having a second diameter smaller than the first diameter of the first step 717. A ramp 730 may be provided between the first step 717 and the second step 719 to deflect at least one retaining member 368 associated with the plunger 326 in a radially inward direction during the connection of the plunger 326 to the distal portion or distal end 726 of the plunger engagement sleeve 714.

[0282] After describing the structure of the plunger 326 (refer to the disclosure herein with reference to Figures 6 to 8C) and piston 700 according to one non-limiting embodiment of the present invention, a method for engaging and disengaging the plunger 326 and piston 700 will now be described with reference to Figures 21A to 21B. Figures 21A to 21B show a portion of the syringe 300.

[0283] Figure 21A shows the piston 700 and its plunger engagement mechanism 712 in a disengaged position or state before locking engagement with the plunger 326. In some embodiments, the piston 700 can be advanced distally using a drive mechanism 402 operated by the controller 200 (Figure 2). In other embodiments, the piston can be moved manually in the distal direction.

[0284] As the piston 700 advances distally, a latch 374 on at least one retaining member 368 of the plunger 326 deflects radially outward due to contact with the locking lip 729 on the plunger portion 721. The plunger engagement post 718 is in its disengaged position and moves axially relative to the plunger engagement sleeve 714 in a distal direction, allowing the retaining member 368 to deflect radially outward into the space defined by the first step 717. After the latch 374 is proximal to the locking lip 729, at least one retaining member 368 can be resiliently deflected radially inward, for example, due to the resiliently flexible engagement of the retaining member 368 with the ramp 730 between the first step 717 and the second step 719. When at least one retaining member 368 is in the position shown in FIG. 21A, the plunger 326 is not locked into engagement with the piston 700 because at least one retaining member 368 can be flexibly deflected in a radially outward direction as the proximal end of the piston 700 moves or the distal end of the plunger 326 moves (such as due to the removal of the syringe by the injector), as described herein.

[0285] Referring to Figure 21B, the plunger engagement pin 718 moves from a disengaged position or state to an engaged position or state by moving in a proximal direction along one of the longitudinal piston axes 720. This movement of the plunger engagement pin 718 can be attributed to the actuator being de-energized and allowing a resiliently retractable member (such as the resiliently retractable member 484 described herein with reference to Figures 9 to 13J) to axially advance the plunger engagement pin 718 in a proximal direction, or alternatively by energizing the actuator to move the plunger engagement pin 718 in a proximal direction. The proximal movement of the plunger engagement pin 718 locks at least one retaining member 368 and the stop 374 in the space defined by the second step 719 of the plunger engagement sleeve 714. Due to the combination of the second smaller diameter of the second step 719 and the increased diameter of the locking lip 729, one or more retaining members 368 of the plunger 326 are captured within the receiving space 715 between the plunger engagement sleeve 714 and the plunger engagement post 718, such that the reciprocating axial movement of the piston 700 causes a corresponding reciprocating axial movement of the plunger 326 within the syringe barrel 318. To unlock the plunger 326 from the plunger engagement mechanism 712, the plunger engagement post 718 is moved to a disengaged position via axial movement in the distal direction to distally move the locking lip 729, allowing the latch 374 of one or more retaining members 368 to move around the locking lip 729 in the first step 717 and allowing one or more retaining members 368 of the plunger 326 to be removed from the receiving space 715 between the plunger engagement sleeve 714 and the plunger engagement post 718.

[0286] Referring to Figures 22A to 22E, a piston 800 and a plunger engagement mechanism 812 according to another embodiment of the present invention are shown. The components of the piston 800 and plunger engagement mechanism 812 shown in Figures 22A to 22E are substantially similar to or identical to the components of the piston 400 and plunger engagement mechanism 412 described herein with reference to Figures 9 to 13J. Therefore, except that the first digit of the component symbols used in Figures 22A to 22E has changed from "4" to "8", the component symbols in Figures 22A to 22E are used to depict the same components as the corresponding component symbols in Figures 9 to 13J. Since the previous discussion regarding the piston 400 and plunger engagement mechanism 412 generally shown in Figures 9 to 13J is applicable to the piston 800 and plunger engagement mechanism 812 shown in Figures 22A to 22E, the following discussion will only focus on the relative differences between the components shown in these figures.

[0287] Referring to Figure 22A, piston 800 has a body 804 and a piston head 806 at a distal end of the body 804. Piston head 806 is configured for removable connection to a plunger of a syringe, such as plunger 326 shown in Figure 8C. A plunger engagement mechanism 812 is integrated into piston head 806. In some embodiments, at least a portion of piston head 806 and / or plunger 326 may be made of a transparent or translucent material configured to allow light emitted by one or more lamps 803 in piston 800 to pass through and illuminate plunger 326 and / or at least a portion of syringe 300.

[0288] Piston 800 has a sensing element 805, such as a sensing sleeve 807 and a sensor 809. The sensing sleeve 807 has a proximal end 813 configured to interact with the sensor 809 when a distal end 815 of the sensing sleeve 807 is advanced in a proximal direction (e.g., due to contact between the distal end 815 of the plunger 326 and the distal end 815 of the sensing sleeve 807). The sensing sleeve 807 may extend along a longitudinal axis 820 of piston 800 and may be recessed within piston head 806. The sensing sleeve 807 is operable to sense contact with a surface (such as a surface of the plunger 326), and a controller 200 may be signaled to control movement of piston 800 based on sensing conditions. In some embodiments, the distal end 815 of the sensing sleeve 807 may be configured to contact one or more retaining members 368 of the plunger 326 when the plunger 326 is connected to piston 800. An initial contact between the distal end 815 of the sensing sleeve 807 and one or more retaining members 368 of the plunger 326 can cause the sensing sleeve 807 to retract in a proximal direction, thereby activating the sensor 809. The sensor 809 is operatively connected to the controller 200 and the drive mechanism of the piston 800 such that after the sensor 809 is activated by the sensing sleeve 807, the sensor 809 signals to the controller 200 to control the movement of the drive mechanism. For example, the drive mechanism can stop or slow down from a first rate to a second slower rate. The sensing sleeve 807 can be biased to its distal position by a biasing member (such as a spring 817).

[0289] The plunger engagement mechanism 812 has a plunger engagement sleeve 814 with a central opening 816 and a plunger engagement post 818. Due to actuation of an actuator (such as actuator 422 described herein with reference to Figures 9 to 13J), the plunger engagement post 818 is translatable relative to the plunger engagement sleeve 814 along the longitudinal piston axis 820. In some embodiments, the plunger engagement post 818 is axially movable between an engagement position in which the plunger 326 is locked into engagement with the piston 800 due to a locking rib 834 on the plunger engagement sleeve 814 and a latch 374 under the plunger engagement post 818 that captures at least one retaining member 368 of the plunger 326, and a disengaged position in which the plunger 326 is removable from the piston 800.

[0290] The plunger engagement sleeve 814 has a hollow body 824, wherein at least a portion of the outer surface of the hollow body 824 defines at least a portion of the piston head 806. A distal portion or distal end 826 of the plunger engagement sleeve 814 is shaped to be received within the cavity 340 of the plunger 326, and at least a portion of the plunger 326 (such as at least one retaining member 368) is configured to be received within a central opening 816. The central opening 816 extends through the hollow body 824 of the plunger engagement sleeve 814.

[0291] One inner surface of the central opening 816 has a locking rib 834 projecting radially inward from the inner surface 828. The locking rib 834 is configured to deflect at least one retaining member 368 associated with the plunger 326 in a radially inward direction during the engagement of the plunger 326 with the distal portion or distal end of the plunger engagement sleeve 814. In some embodiments, the locking rib 834 extends continuously or discontinuously around the inner surface 828 of the hollow body 824 of the plunger engagement sleeve 814 and defines one surface of at least one latch 374 on the at least one retaining member 368 on the engaging plunger 326 to prevent the plunger 326 from being removed from the piston 800 when the plunger is locked into engagement with the plunger engagement mechanism 812, as described herein.

[0292] After describing the structure of the plunger 326 and piston 800 according to one non-limiting embodiment of the present invention, a method for engaging and disengaging the plunger 326 and piston 800 will now be described with reference to Figures 22A to 22E.

[0293] Figure 22A shows the piston 800 and its plunger engagement mechanism 812 in a disengaged position or state before locking engagement with the plunger 326. In some embodiments, the piston 800 can be distally advanced using a drive mechanism 402 operated by the controller 200 (Figure 2). In other embodiments, the piston can be manually moved in the distal direction.

[0294] Moving from Figure 22A to Figure 22B, as the piston 800 advances toward the plunger 326, at least one retaining member 368 on the plunger 326 contacts the sensing sleeve 807, causing the sensing sleeve 807 to move proximally toward the sensor 809. A latch 374 on the at least one retaining member 368 on the plunger 326 deflects in a radially inward direction due to contact with a locking rib 834 on the plunger engaging sleeve 814. The plunger engaging post 818 is in its disengaged position, for example, retracted proximally. When the at least one retaining member 368 is in the position shown in Figure 22B, the plunger 326 is not locked into engagement with the piston 800 because the at least one retaining member 368 can flexibly deflect in a radially inward direction as the piston 800 moves proximally or the plunger 326 moves distally (e.g., due to the removal of the syringe from the injector).

[0295] Referring to Figure 22C, as the sensing sleeve 807 moves proximally due to contact with at least one retaining member 368 of the plunger 326, the sensor 809 detects the presence of the sensing sleeve 807 and actuates the actuator 822 to axially move the plunger engagement post 818 from a disengaged position or state to an engaged position or state in a distal direction. This movement of the plunger engagement post 818 can be attributed to de-energizing the actuator 822. In other embodiments, the movement of the plunger engagement post 818 can be attributed to energizing the actuator 822 (such as a solenoid) or by operating a motor to move the actuator.

[0296] As the plunger engagement post 818 moves from a disengaged state or position to an engaged state or position, the receiving space 815 between the plunger engagement sleeve 814 and the plunger engagement post 818, near the locking rib 834, closes to prevent the latch 374 of one or more retaining members 368 of the plunger 326 from being removed from the receiving space 815. As the plunger engagement post 818 moves to the engaged position or state, the latch 374 of at least one retaining member 368 of the plunger 326 is engaged between the locking rib 834 on the plunger engagement sleeve 814 and the plunger engagement post 818. The piston 800 and the connecting plunger 326 can then reciprocate within the syringe barrel 318. In some embodiments, the piston 800 can advance distally to deliver fluid from the syringe 300 or proximally to fill the syringe 300 with fluid using a drive mechanism 402 operated by the controller 200 (FIG. 2).

[0297] Referring to Figure 22D, for the piston engagement mechanism 812 to unlock the piston 326, the piston engagement post 818 is moved to a disengaged position by axial movement in the distal direction (e.g., by means of an actuator (as described herein) or by a stored restoring force from one of the biasing members), which allows one or more retaining members 368 of the piston 326 to be removed from the receiving space 815 between the piston engagement sleeve 814 and the piston engagement post 818. Removal of the piston 326 from the piston 800 allows the sensing sleeve 807 to move in a distal direction due to a restoring force provided by the spring 817 (Figure 22E).

[0298] Referring to Figures 23A to 23G, a piston 900 and a plunger engagement mechanism 912 according to another embodiment of the present invention are shown. The components of the piston 900 and plunger engagement mechanism 912 shown in Figures 23A to 23G are substantially similar to or identical to the components of the piston 400 and plunger engagement mechanism 412 described herein with reference to Figures 9 to 13J. Since some features previously discussed with respect to the piston 400 and plunger engagement mechanism 412 generally shown in Figures 9 to 13J are applicable to the piston 900 and plunger engagement mechanism 912 shown in Figures 23A to 23G, the following discussion will only address the relative differences between the components shown in these figures.

[0299] Referring to FIG. 23A, the plunger 326 has at least one retaining member 368 having a lever 374 that projects radially outward relative to the plunger's longitudinal axis 334. The lever 374 is shaped to be received within at least a portion of the piston engagement mechanism 912. In some embodiments, the lever 374 has a circular or angled lever surface 375 forming an acute or obtuse angle relative to the plunger's longitudinal axis 334. The angled lever surface 375 is configured to interact with at least a portion of the plunger engagement mechanism 912 during engagement of the plunger 326 with the piston 900, as described herein. The at least one retaining member 368 may also have at least one circular or angled release surface 369. The angled release surface 369 may be disposed on at least a portion of the lever 374, such as opposite the angled lever surface 375. The circular or angled release surface 369 forms an acute or obtuse angle relative to the longitudinal axis 334 of the plunger in a direction opposite to the arc or angle of the circular or angled stop surface 375. The circular or angled release surface 369 is configured to interact with at least a portion of the plunger engagement mechanism 912 during disengagement of the plunger 326 from the piston 900, as described herein. In various embodiments, without additional support, the frictional and locking interaction between the circular or angled release surfaces 369 is insufficient to lock the plunger engagement mechanism 912 engaging the plunger 326 and the piston 900.

[0300] Piston 900 can extend and retract from the housing of fluid injectors 10, 100 (FIGs 1 and 3). Piston 900 includes a rod 901 and a piston head 920 formed on a distal end of the rod 901. In some embodiments, piston head 920 can extend radially outward beyond the radial edge of rod 901. Piston head 920 can be substantially cylindrical in structure, having a piston cavity 940 configured to receive at least a portion of plunger 326 (such as at least one retaining member 368) when plunger 326 is engaged with piston 900. Piston cavity 940 can have at least one locking lip 950 projecting radially inward from an inner surface of piston cavity 940. At least one locking lip 950 is configured to engage at least a portion of retaining member 368, such as latch 374. At least one locking lip 950 can be continuous or discontinuous in a circumferential direction surrounding piston cavity 940.

[0301] In some instances, at least one locking lip 950 has a circular or angled distal surface 960 and a circular or angled proximal surface 970. The circular or angled distal surface 960 is arcuate or angled in one of the directions of the circular or angled stop surface 375 of the plunger 326. In this way, the distal surface 960 engages the stop surface 375 during the connection procedure between the piston 900 and the plunger 326 to allow one or more retaining members 368 to flexibly and elastically deflect in a radially inward direction toward one of the longitudinal axes 334 of the plunger to allow the plunger 326 to be inserted into the piston chamber 940. The circular or angled proximal surface 970 is arcuate or angled in one of the directions opposite to that of the circular or angled distal surface 960. The circular or angled proximal surface 970 is arcuate or angled in one of the directions of the circular or angled release surface 369 of the plunger 326. In this manner, the proximal surface 970 engages the release surface 369 to disconnect the plunger 326 from the piston 900 during axial movement of the piston 900 and / or plunger 326. The engagement between the release surface 369 on the plunger 326 and the proximal surface 970 on the piston 900 causes one or more retaining members 368 to deflect in a radially inward direction toward one of the longitudinal axes 334 to allow the plunger 326 to be withdrawn from the piston chamber 940.

[0302] Referring to Figures 23A to 23G, piston 900 has a locking member 980 configured to lock one of the plungers 326 relative to piston 900. Locking member 980 is axially movable between a first position (Figure 23D) and a second position (Figure 23E). In some embodiments, locking member 980 is movable such that it extends at least partially within piston cavity 940. When extended in the second position, locking member 980 is inserted into cavity 340 of plunger 326 to prevent at least one retaining member 368 from deflecting in a radially inward direction. For example, in the second engaged position, locking member 980 locks latch 374 against at least one locking lip 950 by bringing a release surface 369 on plunger 326 against proximal surface 970 on piston 900, preventing latch 374 from moving through at least one locking lip 950. In some embodiments, a sensing element (not shown) (such as a spring-loaded pin connected to a sensor) may be provided for sensing contact with a surface (such as a surface of the plunger 326) and controlling the movement of one of the pistons 900 based on the sensing conditions.

[0303] After describing the structure of the plunger 326 and piston 900 according to a non-limiting embodiment, the engagement and disengagement of the plunger 326 and piston 900 will now be described with reference to Figures 23A to 23G. For clarity, the remaining portion of the syringe 12 shown in Figure 23A from Figures 23B to 23G is omitted.

[0304] To engage plunger 326 and piston 900, syringe 12 is first inserted into syringe port 16 or pressure sleeve 15 (Figure 3) of fluid injector 10 (Figure 1). Once syringe 12 is inserted into syringe port 16, various locking mechanisms (not shown) are available to retain syringe 12 within syringe port 16 or pressure sleeve to prevent syringe 12 from being dislodged from syringe port 16. First, plunger 326 may be positioned at the proximal end 20 of syringe barrel 18. Then, piston 900 may advance toward the distal end of plunger 326 to engage piston head 920 with plunger 326.

[0305] Referring to Figures 23A and 23B, the piston 900 advances axially in a distal direction (arrow A in Figures 23A and 23B) such that the angled distal surface 960 of the piston head 920 contacts at least one retaining member 368 of the plunger 326. First, the angled distal surface 960 contacts a latch 374, such as a latch surface 375, of the at least one retaining member 368. Because the latch 374 protrudes radially outward relative to the at least one retaining member 368, the latch 374 is positioned a radial distance further away from the longitudinal axis 334 of the plunger than the inner surface of the piston cavity 940 near the angled distal surface 960. In this way, continued distal movement of the piston 900 causes the at least one retaining member 368 to flexibly and elastically deflect radially inward due to the contact between the latch surface 375 on the plunger 326 and the distal surface 960 on the piston 900 (Figure 23B). In an example having a plurality of retaining members 368, each of the retaining members 368 is radially inwardly deflected relative to the longitudinal axis 334 of the plunger.

[0306] Referring to Figure 23C, during the continued axial movement of the piston 900 in a distal direction, the latch 374 advances axially through at least one lip 950 of the piston head 920. Due to a restoring force generated during radial deflection of at least one retaining member 368, the latch 374 engages radially outward into a recess 990 located proximal to the at least one locking lip 950 (Figure 23A). Thus, the plunger 326 is releasably retained within the piston chamber 940. To lock the plunger 326 to the piston 900 and prevent the plunger 326 from being removed from the piston 900, the locking member 980 extends from a first position (Figure 23D) to a second position (Figure 23E) by moving the locking member 980 in the axial direction (arrow B). In the second position, the locking member 980 is positioned such that the retaining member 368 is locked between an inner surface of the piston chamber 940 and an outer surface of the locking member 980 and cannot be flexibly deflected inward to disengage. Locking member 980 prevents retaining member 368 from moving in a radially inward direction, thereby preventing plunger 326 from disengaging from piston 900. In this way, piston 900 can move in a proximal or distal direction, causing corresponding movement of plunger 326. Locking member 980 can be moved between a disengaged position and an engaged position by an electromechanical actuator (such as a solenoid actuator, a rotary motor, a linear motor, or the like). As shown in Figures 23A and 23B, locking member 980 can be reciprocated using a rotary motor to rotate the interlocking surfaces of a threaded screwdriver.

[0307] To unlock the syringe 12 from the syringe port 16 and disengage the plunger 326 from the piston 900, the locking member 980 moves axially from the second position to the first position by one of the directions indicated by arrow C in FIG. 23F. When the locking member 980 is in the first position, the plunger 326 can be disengaged from the piston 900 by moving the plunger 326 via the syringe 12 in a distal direction (arrow D in FIG. 23G) and / or by moving the piston 900 in a proximal direction. This relative movement between the piston 900 and the plunger 326 causes the angled release surface 369 of the retaining member 368 to engage the angled proximal surface 970 of the piston 900. Continued movement of the plunger 326 away from the piston 900 causes the retaining member 368 to deflect radially inward to clear the lip 950. After clearing the lip 950, the retaining member 368 springs back in a radially outward direction, thereby completely disengaging the plunger 326 from the piston 900.

[0308] Referring to Figures 24A to 24C, a piston 1000 and a plunger engagement mechanism 1012 according to another embodiment of the present invention are shown. The components of the piston 1000 and plunger engagement mechanism 1012 shown in Figures 24A to 24C are substantially similar to or identical to the components of the piston 400 and plunger engagement mechanism 412 described herein with reference to Figures 9 to 13J. Therefore, except that the first digit of the component symbols used in Figures 24A to 24C has changed from "4" to "10", the component symbols in Figures 24A to 24C are used to depict the same components as the corresponding component symbols in Figures 9 to 13J. Since the previous discussion regarding the piston 400 and plunger engagement mechanism 412 generally shown in Figures 9 to 13J is applicable to the piston 1000 and plunger engagement mechanism 1012 shown in Figures 24A to 24C, the following discussion will only focus on the relative differences between the components shown in these figures.

[0309] Referring to FIG. 24B, the plunger engagement mechanism 1012 has a plunger engagement sleeve 1014 having a central opening 1016 and a plunger engagement post 1018 reciprocating within the central opening 1016 of the plunger engagement sleeve 1014 in one direction of a longitudinal piston axis 1020. The plunger engagement post 1018 is reciprocated by an actuator (such as actuator 422 shown herein with reference to FIG. 9 or other embodiments of the plunger engagement mechanism described herein). The plunger engagement mechanism 1012 is operable between an engaged position or state and a disengaged position or state. In the engaged position or state, the plunger engagement post 1018 may be positioned within the plunger engagement sleeve 1014 to capture at least one retaining member 368 associated with the plunger 326 (as shown in FIG. 24C) in a receiving space 1015 between the plunger engagement sleeve 1014 and the plunger engagement post 1018. Conversely, in the disengaged position or state, the plunger engagement post 1018 may be positioned relative to the plunger engagement sleeve 1014 to allow removal of at least one retaining member 368 associated with the plunger 326 from the receiving space 1015 between the plunger engagement sleeve 1014 and the plunger engagement post 1018.

[0310] Referring to Figure 24B, the plunger engagement sleeve 1014 has a hollow body 1024, wherein at least a portion of an outer surface of the hollow body 1024 defines at least a portion of the piston head 1006. A distal portion or distal end 1026 of the plunger engagement sleeve 1014 is shaped to be received within the cavity 340 of the plunger 326, and at least a portion of the plunger 326 (such as at least one retaining member 368) is configured to be received within a central opening 1016. The central opening 1016 extends through the hollow body 1024 of the plunger engagement sleeve 1014. An outer surface 1042 of the plunger engagement sleeve 1014 may have a toothed portion 1044. The toothed portion 1044 may be configured to interact with a corresponding toothed portion 329 on the plunger 326 during rotation of the plunger 326 relative to the piston 1000.

[0311] The plunger engagement sleeve 1014 further includes at least one locking groove 1065 recessed into the inner surface of the central opening 1016. In some embodiments, the at least one groove 1065 may be configured to receive a latch 374 of at least one retaining member 368 of the plunger 326 when the plunger 326 is engaged with the plunger engagement sleeve 1014.

[0312] The plunger engagement post 1018 has a shaft 1072 comprising a proximal end 1074 and a distal end 1076. The distal end 1076 of the shaft 1072 has a tapered end face 1078 configured to contact at least one retaining member 368 on the plunger 326 to flexibly deflect the at least one retaining member 368 in a radially inward direction when the piston 1000 contacts the plunger 326. When moved into the engaged position, the plunger engagement post 1018 prevents the plunger 326 from being removed from the piston 1000 (as shown in FIG24C), for example by locking the at least one retaining member 368 of the plunger 326 under a locking groove 1065 on the plunger engagement sleeve 1014 by a latch 374 that locks the at least one retaining member 368 of the plunger 326. The proximal end 1074 of shaft 1072 is configured to be connected to an actuator (similar to actuator 422 described herein with reference to Figures 9 to 13J) to move plunger engagement pin 1018 relative to plunger engagement sleeve 1014 between an engaged position or state and a disengaged position or state.

[0313] Referring to FIG. 24C, the proximal end 1074 of shaft 1072 is received within a rotating mechanism 1071, which is slidably mounted within the hollow body 1024 of plunger engagement sleeve 1014. In some embodiments, the rotating mechanism 1071 may be configured for unidirectional rotation, such as in a clockwise or counterclockwise direction about one of the longitudinal piston axes 1020, as described in the various embodiments herein. For example, the rotating mechanism 1071 may be a one-way clutch.

[0314] After describing the structure of the plunger 326 and piston 1000 according to one non-limiting embodiment of the present invention, a method for engaging and disengaging the plunger 326 and piston 1000 will now be described.

[0315] Figure 24C shows the piston 1000 and its plunger engagement mechanism 1012 in an engaged position or state with one of the plungers 326. As described herein with reference to Figures 13A to 13J, the plunger 326 can be connected to the piston 1000 by distally moving the piston 1000 to allow one or more retaining members 368 of the plunger 326 to be inserted into the receiving space 1015 between the plunger engagement sleeve 1014 and the plunger engagement post 1018, such that the latch 374 is located within the locking groove 1065. In some embodiments, the piston 1000 can be distally advanced using a drive mechanism 402 operated by the controller 200 (Figure 2). In other embodiments, the piston 1000 can be manually moved in the distal direction.

[0316] The piston 1000 advances axially in a distal direction such that at least one retaining member 368 of the plunger 326 is received within the central opening 1016 of the plunger engagement sleeve 1014, such that at least one retaining member 368 is radially inwardly deflected due to contact between the latch 374 and the inner surface of the plunger engagement sleeve 1014. In embodiments having a plurality of retaining members 368, each of the retaining members 368 is deflected in a radially inward direction.

[0317] During the continued axial movement of the piston 1000 in a distal direction, the deflector 374 deflects radially outward into the locking groove 1065 of the piston engagement sleeve 1014. After the deflector 374 is positioned within the locking groove 1065, the distal movement of the piston 1000 relative to the plunger 326 stops, for example, due to engagement between the toothed portion 329 on the plunger 326 and the toothed portion 1044 on the outer surface 1042 of the plunger engagement sleeve 1014. The plunger engagement pin 1018 is in the disengaged position or state and the plunger 326 is connected to the piston 1000, with the toothed portion 329 on the plunger 326 aligned with the toothed portion 1044 on the outer surface 1042 of the plunger engagement sleeve 1014.

[0318] As the plunger engagement post 1018 moves from a disengaged state or position to an engaged state or position, the receiving space 1015 between the plunger engagement sleeve 1014 and the plunger engagement post 1018 closes to prevent one or more retaining members 368 of the plungers 326 from being removed from the receiving space 1015 and the locking groove 1065. As the plunger engagement post 1018 moves to the engaged position or state, at least one retaining member 368 of the plungers 326 is engaged between the outer surfaces of the plunger engagement sleeve 1014 and the plunger engagement post 1018. The piston 1000 and the connecting plunger 326 can then reciprocate within the barrel 318 of the syringe 300. In some embodiments, the piston 1000 can advance distally to deliver fluid from the syringe 300 or proximally to fill the syringe 300 with fluid using a drive mechanism 402 operated by the controller 200 (FIG. 2).

[0319] To unlock the syringe 300 from the syringe port of the injector and disengage the plunger 326 from the piston 1000, the syringe 300 rotates clockwise or counterclockwise relative to the syringe port about the syringe longitudinal axis. Rotation of the plunger 326 also causes rotation of the plunger engagement sleeve 1014, due to the alignment of the toothed portion 329 on the plunger 326 with the toothed portion 1044 on the plunger engagement sleeve 1014. Because the plunger engagement pin 1018 is connected to the plunger engagement sleeve 1014 via a rotating mechanism 1071, the plunger engagement pin 1018 does not rotate with the rotation of the plunger engagement sleeve 1014. In some embodiments, the plunger engagement pin 1018 may be moved between an engaged position and a disengaged position via an actuator (such as actuator 422 described herein with reference to Figures 9 to 13J).

[0320] Figures 25A and 25B illustrate an embodiment of a piston-plunger engagement system according to another embodiment. Figure 25A shows a disengaged position of the system, wherein the plunger includes an inwardly facing engagement flange or latch 2774 extending proximally from an inner surface of a plunger base. The piston includes at least one flexible retaining member 2750 having at least one retaining latch 2755 configured to engage a corresponding engagement flange or latch 2774 of the plunger base. In the disengaged position, a movable locking member 2798 is configured in a distal first position such that the locking member 2798 is not engaged with at least one flexible retaining member 2750 of the piston 2700. As shown in Figure 25B, the piston-plunger engagement system is in the engaged position, wherein the movable locking member 2798 is moved in the proximal direction by, for example, a motor, solenoid, or cam system. As the locking member 2798 moves proximally, a proximal surface 2799 (e.g., the angled surface illustrated in Figures 25A and 25B) contacts and engages at least one flexible retaining member 2750 to flex the retaining member 2750 in a radially outward direction. As the retaining member 2750 moves radially outward, at least one retaining latch 2755 engages at least one inwardly facing engagement flange or latch 2774 to lock the plunger base to the piston. Generally, at least one inwardly facing engagement flange or latch 2774 is substantially non-flexible, for example due to structural strength or the outer surface of the plunger engagement sleeve 2714, which prevents the engagement flange or latch 2774 from flexing radially outward and disengaging from at least one retaining latch 2755 of the at least one flexible retaining member 2750. Moving the locking member 2798 in the distal direction releases the force applied to at least one flexible retaining member 2750 to allow the retaining member 2750 to return to a non-flexible, disengaged position, wherein at least one retaining latch 2755 does not contact or engage at least one inwardly engaging flange or latch 2774 and allows the plunger to be removed from the piston.

[0321] In some embodiments, a resilient telescopic member 2784 may be configured to bias the locking member 2798 toward a disengaged or engaged position. For example, the resilient telescopic member 2784 may be a compression spring configured to bias the locking member 2798 in a distal direction toward a disengaged position. In this manner, the locking member 2798 is in a normally disengaged state such that, upon power failure, the plunger can be disconnected from the locking member 2798. In other embodiments, the resilient telescopic member 2784 may be a tension spring configured to bias the locking member 2798 in a proximal direction toward an engaged position. In these embodiments, the locking member 2798 is in a normally engaged position and must be moved to a disengaged position (such as using an actuator 422 described herein with reference to FIG9) to allow the plunger to be removed from the locking member 2798.

[0322] Referring to FIG. 26, a piston 1100 having a plunger engagement mechanism 1112 according to another embodiment of the present invention is shown. In some embodiments, the piston 1100 may be configured for use with the injectors 10, 100 shown in FIG. 1 and 3. In other embodiments, the piston 1100 may be configured for use with any fluid injector configured for medical purposes, such as injecting contrast fluid and saline in a contrast-enhanced imaging procedure. The piston 1100 is configured for reciprocating movement within the housing of the injector via a drive mechanism. The drive mechanism may include, for example, an electric motor 402 (FIG. 2), a hydraulic system, a pneumatic system, or any combination thereof. A controller 200 (FIG. 2) may be configured to control the operation of the drive mechanism and, consequently, control the reciprocating movement of the piston 1100.

[0323] Piston 1100 has a body 1104 and a piston head 1106 at a distal end of the body 1104. Piston head 1106 is configured for removable connection to plunger 326 of syringe 300. Piston head 1106 has a substantially cylindrical structure with a partially conical distal end configured to be received within at least a portion of a cavity 340 receiving plunger 326. In some embodiments, piston head 1106 and / or at least a portion of plunger 326 may be made of a transparent or translucent material configured to allow light emitted by one or more lamps of piston 1100 to pass through and illuminate plunger 326 and / or at least a portion of syringe 300.

[0324] The piston head 1106 has a plunger engagement mechanism 1112 configured to releasably engage the plunger 326 to facilitate reciprocating drive of the plunger 326 within the barrel of the syringe 300 and to immediately remove the syringe 300 and plunger 326 from the piston head 1106 and the fluid injector at the end of an injection procedure. The plunger engagement mechanism 1112 has a plunger engagement sleeve 1114 with a central opening 1116 and a plunger engagement pin 1118 reciprocating within the central opening 1116 of the plunger engagement sleeve 1114 along a longitudinal piston axis 1120. The plunger engagement pin 1118 is reciprocated by an actuator 1122 of the fluid injector. The plunger engagement mechanism 1112 is operable between an engaged position or state and a disengaged position or state. In the engaged position or state, the plunger engagement post 1118 may be positioned within the plunger engagement sleeve 1114 to capture at least one retaining member 368 associated with the plunger 326 in a receiving space 1115 between the plunger engagement sleeve 1114 and the plunger engagement post 1118. Conversely, in the disengaged position or state, the plunger engagement post 1118 may be positioned relative to the plunger engagement sleeve 1114 to allow removal of at least one retaining member 368 associated with the plunger 326 from the receiving space 1115 between the plunger engagement sleeve 1114 and the plunger engagement post 1118.

[0325] Actuator 1122 can be configured to have an engaged state for moving one of the plunger engagement sleeve 1114 and plunger engagement post 1118 to an engaged position and a disengaged state for moving one of the plunger engagement sleeve and plunger engagement post to a disengaged position. In some embodiments, actuator 1122 can automatically move to the disengaged state, such as during a power outage of actuator 1122. In some embodiments, actuator 1122 can be in the engaged state only during proximal movement of piston 1100. In some embodiments, actuator 1122 can be a solenoid configured to be primarily in the disengaged state and can be in the engaged state only during the connection of plunger 326 to piston 1100. In other embodiments, actuator 1122 can be a rotary electric motor, a linear electric motor, or a linear actuator. In some embodiments, actuator 1122 is a linear actuator that can be manually reverse-driven when the injector is de-energized. In various embodiments, moving one of the plunger engagement sleeve 1114 and the plunger engagement pin 1118 to a disengaged state to remove the plunger 326 from the piston 1100 can be accomplished by rotating the plunger 326 relative to the piston 1100, as described herein.

[0326] Referring to FIG. 27A, a plunger engagement sleeve 1114 according to one embodiment is described. The plunger engagement sleeve 1114 has a hollow body 1124, wherein at least a portion of an outer surface of the hollow body 1124 defines at least a portion of a piston head 1106 (FIG. 26). In some embodiments, a distal portion or distal end 1126 of the hollow body 1124 may have a conical shape configured to correspond to the shape of the cavity 340 of the conical portion of the plunger 326. At least a portion of the plunger 326 (such as at least one retaining member 368) is configured to be received within a central opening 1116. The central opening 1116 extends through the hollow body 1124 of the plunger engagement sleeve 1114. A proximal end or proximal portion 1132 of the hollow body 1124 may be configured to be received within a plunger release sleeve 1158 (as shown in FIG. 28).

[0327] At least a portion of the outer surface 1142 of the hollow body 1124 has a toothed portion 1144 configured to interact with one or more release lugs 380 on the plunger 326 during attachment and removal of the plunger 326 from the plunger engagement mechanism 1112, as described herein. The toothed portion 1144 has one or more plunger release teeth 1145 projecting from the outer surface 1142. The one or more plunger release teeth 1145 may project radially outward from the outer surface 1142 of the hollow body 1124. The one or more plunger release teeth 1145 are separated from each other by portions of the outer surface 1142 of the hollow body 1124, such that grooves are formed between adjacent plunger release teeth 1145. In embodiments in which two or more plunger release teeth 1145 are provided, the plunger release teeth 1145 may be uniformly spaced from each other. In some embodiments, the plunger release teeth 1145 may have unequal angular extensions and / or unequal angular spacings. The radial spacing of the plunger release teeth 1145 can be selected to correspond to the spacing between one or more release lugs 380 on the plunger 326. The distal end 1147 of each of the plunger release teeth 1145 may have a tip 1149 configured to self-guide one of the release lugs 380 on the plunger 326 during connection of the plunger 326 to the plunger engagement sleeve 1114. As described herein, one or more plunger release teeth 1145 are configured to interact with one or more release lugs 380 on the plunger 326 to achieve piston release of the plunger 326 during rotation of the plunger 326 about its longitudinal axis 334, such as rotation attributable to the syringe 300.

[0328] Referring to FIG27B, a portion of the inner surface 1128 of the central opening 1116 at the distal end of the opening 1116 may have a bevel 1130 such that the inner diameter of the opening 1116 narrows in a direction from the distal end 1126 of the hollow body 1124 toward a proximal portion or proximal end 1132. In some embodiments, the bevel 1130 may be configured to deflect at least a portion of at least one retaining member 368 associated with the plunger 326 in a radially inward direction during connection of the plunger 326 to the distal portion or distal end 1126 of the plunger engagement sleeve 1114. In other embodiments, the bevel 1130 may define a clearance space for at least a portion of at least one retaining member 368 (such as a latch 374) during connection of the plunger 326 to the plunger engagement sleeve 1114. The inner surface 1128 of the central opening 1116 may have an inclined inner diameter that decreases in the direction from the distal end 1126 of the plunger engagement sleeve 1114 toward the proximal end of the plunger engagement sleeve 1114. For example, the opening 1116 may have a first inner diameter at the proximal end of the ramp 1130 and a second diameter smaller than the first diameter at the distal end of the ramp 1130. The inner surface 1128 of the central opening 1116 may be substantially cylindrical at the proximal end of the ramp 1130. In other embodiments, one or both portions of the inner surface 1128 before and after the ramp 1130 may have a slight inclination at an angle in the same direction as the ramp 1130.

[0329] Referring to Figures 26 and 28, a plunger release sleeve 1158 surrounds at least a portion of a plunger engagement sleeve 1114. In some embodiments, the plunger release sleeve 1158 has a hollow body 1159 having an inner cavity 1161 configured to receive a proximal end or proximal portion 1132 of the plunger engagement sleeve 1114. In some embodiments, the plunger release sleeve 1158 has a cylindrical sidewall 1160 including an opening 1162 extending therethrough. The opening 1162 may have a longitudinal surface 1163 substantially parallel to a longitudinal axis 1164 of the plunger release sleeve 1158 and an inclined surface 1166 connected to the longitudinal surface 1163 and angled downward relative to the longitudinal axis 1164 of the plunger release sleeve 1158 in a direction from a distal end 1168 toward a proximal end 1170. As described herein, longitudinal surface 1163 is configured to guide a guide pin 1139 associated with plunger engagement post 1118 during movement of plunger engagement post 1118 in one of the longitudinal directions along the longitudinal axis 1120 of piston 1100, while inclined surface 1164 is configured to guide guide pin 1139 to move plunger engagement post 1118 during rotational movement of plunger 326 relative to piston 1100 (such as during removal of plunger 326 from piston 1100).

[0330] Referring to FIG. 29, the plunger engagement mechanism 1112 further includes a housing 1146 configured to receive one of the actuators 1122. The housing 1146 has a proximal portion 1152 connected to a distal portion 1154. In some embodiments, the distal portion 1154 may have an outer diameter smaller than that of the proximal portion 1152, such that a protrusion 1156 is defined at a transition between the proximal portion 1152 and the distal portion 1154. In some embodiments, the protrusion 1156 may be configured to support a proximal end of a biasing member 1196 configured to release the plunger 326 from the piston engagement mechanism 1112 during disengagement of the plunger 326 from the piston 1100. In some embodiments, the biasing member 1196 may be a torsion spring having a first end connected to the housing 1146 and a second end connected to a plunger release sleeve 1158.

[0331] Referring to FIG. 26, the plunger engagement sleeve 1114 and the plunger release sleeve 1158 are fixed relative to each other and do not rotate, but both can rotate relative to the plunger release pin 1118 about the longitudinal piston axis 1120 between a first position and a second position, as described herein with reference to FIGS. 30A to 30D. In some embodiments, the plunger engagement sleeve 1114 and the plunger release sleeve 1158 can rotate in one of a clockwise and a counterclockwise direction or a clockwise and a counterclockwise direction. Due to the rotational movement of the plunger 326 about the longitudinal piston axis 1120, the plunger engagement sleeve 1114 and the plunger release sleeve 1158 can rotate from the first position to the second position. For example, due to the interaction between the release lug 380 on the plunger 326 and the toothed portion 1144 on the piston engagement sleeve 1114, the plunger engagement sleeve 1114 and the plunger release sleeve 1158 can rotate about the longitudinal axis 1120. The biasing member 1196 can be configured to bias the plunger engagement sleeve 1114 and the plunger release sleeve 1158 to a first position. In this way, when the plunger engagement sleeve 1114 and the plunger release sleeve 1158 rotate from the first position to the second position, the biasing member 1196 stores potential energy therein, which then assists the plunger engagement sleeve 1114 and the plunger release sleeve 1158 to return to the first position.

[0332] Referring to Figure 29, a plunger engagement post 1118, separated from the plunger engagement mechanism 1112, is shown. The plunger engagement post 1118 has a shaft 1172 comprising a proximal end 1176 and a distal end 1174. The proximal end 1176 of the shaft 1172 is connected to a housing 1146. The distal end 1174 of the shaft 1172 has a tapered or rounded end face 1178 configured to contact at least one retaining member 368 on the plunger 326 to flexibly deflect radially outward as the retaining member 368 passes through the end face 1178. A seal 1180 (Figure 26) may be disposed at the proximal end 1176 to seal the inner surface 1128 of the plunger engagement sleeve 1114. The seal 1180 may be an O-ring seal.

[0333] The plunger engagement post 1118 further includes a guide pin 1139 configured to guide movement of the plunger engagement post 1118 relative to the plunger engagement sleeve 1112 and the plunger release sleeve 1158. In some embodiments, the guide pin 1139 extends through the housing 1146 and is configured substantially perpendicular to one of the longitudinal axes 1120 of the plunger engagement post 1118.

[0334] The plunger engagement post 1118 has a locking groove 1127 of a latch 374 configured to receive at least one retaining member 368 of the plunger 326. The end face 1178 may be shaped to cause at least one retaining member 368 to deflect in a radially outward direction due to contact between the latch 374 and an outer surface of the end face 1178. In this manner, movement of the piston 1100 relative to the distal end of the plunger 326 causes at least one retaining member 368 to deflect radially outward due to contact between the latch 374 and the circular or conical outer surface of the end face 1178.

[0335] The plunger engagement post 1118 has a sensing element 1105, such as a pin 1107 and a sensor 1109. The pin 1107 has a proximal end 1113 configured to contact the sensor 1109 (e.g., due to contact between the plunger 326 and the distal end 1117 of the pin 1107) when one distal end 1117 of the pin 1107 is advanced in a proximal direction. The pin 1107 may extend along a longitudinal axis 1120 of the piston 1100 and may protrude through at least a portion of the piston head 1106. The pin 1107 is operable to sense contact with a surface (such as an inner surface of the plunger 326) and to send one or more signals to a controller 200 of the fluid injector to control movement of the piston 1100 based on sensing conditions. For example, an initial contact between the distal end 1117 of the pin 1107 and the plunger 326 may cause the pin 1107 to retract in a proximal direction, thereby activating the sensor 1109. Sensor 1109 is operatively connected to controller 200, which controls the drive mechanism of piston 1100 such that after sensor 1109 is actuated by pin 1107, sensor 1109 controls the movement of the drive mechanism. For example, the drive mechanism can stop or slow down from a first rate to a second slower rate. Pin 1107 can be biased to its distal position by a spring 1111. A seal 1119 can be disposed between pin 1107 and plunger engagement post 1118 to prevent fluid ingress.

[0336] Referring again to Figure 29, one or more lamps 1173 may be disposed on a printed circuit board 1175 on the base of the plunger engagement post 1118. One or more lamps 1173 may be configured to illuminate at least a portion of the plunger 326 and the plunger engagement sleeve 1114, as described herein.

[0337] After describing the structure of the plunger 326 and piston 1100 according to one non-limiting embodiment of the present invention, a method of engaging the plunger 326 and piston 1100 will now be described with reference to Figures 30A to 30D. Figures 31A to 31D show the plunger engagement mechanism 1112 during various stages of disengagement between the plunger 326 and piston 1100.

[0338] Figure 30A shows the piston 1100 and its plunger engagement mechanism 1112 in a disengaged position or state before engagement with the plunger 326. In some embodiments, the preset state of the plunger engagement mechanism 1112 may be an engaged position or state. In other embodiments, the preset state of the plunger engagement mechanism 1112 may be a disengaged position or state. To connect the plunger 326 to the piston 1100, the syringe 300 is first connected to the injector. During the connection of the syringe 300 to the injector, the piston 1100 is withdrawn from the housing of the injector. After the syringe 300 is connected to the injector, the piston 1100 may advance within the inner bore of the syringe 300 toward one distal end of the plunger 326.

[0339] Referring to Figure 30A, actuator 1122 (shown in Figure 26) is operated to its disengaged position or state, wherein plunger engagement post 1118 is positioned at its distal end. Movement of plunger engagement post 1118 in the distal direction opens receiving space 1115 between plunger engagement sleeve 1114 and plunger engagement post 1118 to allow one or more retaining members 368 of plungers 326 to be inserted into receiving space 1115. Pin 1107 is in its distal position, while guide pin 1139 is located at the distal end 1151 of one of the longitudinal surfaces 1163 of the opening 1162 (Figure 28) on plunger release sleeve 1158.

[0340] Referring to Figure 30B, piston 1100 moves axially toward the distal end of one of the plungers 326 (indicated by arrow A1). In some embodiments, piston 1100 may be advanced distally using a drive mechanism 402 operated by injector controller 200 (Figure 2). In other embodiments, piston may be manually moved distally. Piston 1100 advances axially in a distal direction such that at least one retaining member 368 of plunger 326 is received within a central opening 1116 of plunger engagement sleeve 1114. As piston 1100 advances distally toward plunger 326, at least a portion of one or more retaining members 368 on plunger 326 contacts the tapered end face 1178 of plunger engagement post 1118, causing retaining member 368 to flexibly deflect in a radially outward direction. For example, because the lever 374 protrudes radially inward relative to the second end of each retaining member 368, the lever 374 contacts the tapered surface 1178 of the plunger engagement post 1118, which deflects the retaining member 368 in a radially outward direction. In embodiments having a plurality of retaining members 368, each of the retaining members 368 is deflected in a radially outward direction.

[0341] Referring to Figure 30C, during the continued axial movement of piston 1100 in the distal direction, retaining member 328 is positioned such that latch 374 can be deflected into locking groove 1127 of piston engagement post 1118. After latch 374 is positioned in locking groove 1127, at least one retaining member 368 can be resiliently deflected in a radially inward direction and retaining member 328 can ride upward on ramp 1130 on inner surface 1128 of central opening 1116 and enter into second diameter of inner surface 1128. When at least one retaining member 368 is in the position shown in Figure 30C, plunger 326 is not locked into piston 1100 because at least one retaining member 368 can be deflected in a radially outward direction as piston 1100 moves proximally or plunger 326 moves distally (e.g., due to syringe removal from injector), and latch 374 can be displaced out of locking groove 1127. When the plunger 326 is connected to the piston 1100, one or more release lugs 380 on the plunger 326 align with the toothed portion 1144 on the outer surface 1142 of the plunger engagement sleeve 1114 (FIG. 30A). The pin 1107 of the sensing member 1105 moves axially in a proximal direction due to contact with the plunger 326, such that the proximal end 1113 of the pin 1107 can be detected by the sensor 1109 to signal the controller 200 to stop further distal movement of the piston 1100.

[0342] Referring to Figure 30D, actuator 1122 (Figure 26) is operated to move plunger engagement post 1118 from a disengaged position or state to an engaged position or state in a proximal direction indicated by arrow B1. The distal movement of plunger engagement post 1118 closes the receiving space 1115 between plunger engagement sleeve 1114 and plunger engagement post 1118 to lock latch 374 within locking groove 1127 to prevent one or more retaining members 368 of plunger 326 from being disengaged and removed from the receiving space 1115. Once plunger engagement post 1118 has moved to the engaged position or state, at least one retaining member 368 of plunger 326, including latch 374, is engaged between plunger engagement sleeve 1114 and plunger engagement post 1118, such that axial movement of piston 1100 causes corresponding axial movement of plunger 326 within syringe barrel. As the plunger engagement pin 1118 moves in the proximal direction, the guide pin 1139 moves axially from one distal end 1151 of the longitudinal surface 1163 of the opening 1162 (FIG. 28) on the plunger release sleeve 1158 to one proximal end 1153 in the proximal direction.

[0343] Next, the piston 1100 and the connecting plunger 326 can reciprocate within the barrel 318 of the syringe 300. In some embodiments, the piston 1100 can advance distally to deliver fluid from the syringe 300 or advance proximally to fill the syringe 300 with fluid using a drive mechanism 402 operated by the controller 200 (FIG. 2).

[0344] Referring to Figures 31A to 31D, to unlock the syringe 300 from the syringe port of the injector and disengage the plunger 326 from the piston 1100, the syringe 300 can rotate clockwise or counterclockwise relative to the syringe port about the syringe longitudinal axis 315 (Figure 5B). Because the plunger 326 does not actually rotate within the syringe barrel 318 (due to frictional contact between them), the rotation of the syringe 300 also causes the plunger 326 to rotate relative to the piston 1100 about the longitudinal piston axis 1120. Due to the alignment of one or more release lugs 380 on the plunger 326 with the plunger release teeth 1145 on the toothed portion 1144 of the plunger engagement sleeve 1114, the rotation of the plunger 326 also causes the plunger engagement sleeve 1114 and the plunger release sleeve 1158 to rotate from a first position to a second position relative to the plunger engagement pin 1118. Because the guide pin 1139 on the plunger engagement post 1118 is received within the opening 1162 on the plunger release sleeve 1158, and because the plunger engagement post 1118 does not rotate about the longitudinal piston axis 1120, the rotation of the plunger engagement sleeve 1114 causes the guide pin 1139 to be guided along the inclined surface 1166 of the plunger release sleeve 1158 (see also FIG. 28) from a first position shown in FIG. 30D to a second position shown in FIG. 31A (e.g., from a proximal end of the inclined surface 1166 toward a distal end of the inclined surface 1166). Additionally, the rotation of the plunger engagement sleeve 1114 about the longitudinal piston axis 1120 accumulates potential energy in the biasing member 1196.

[0345] Referring again to Figure 31A, the movement of the guide pin 1139 along the inclined surface 1166 of the plunger release sleeve 1158 causes the plunger engagement pin 1118 to move axially from the engaged position or state to the disengaged position or state in the direction distal to one of the arrows C1. The distal movement of the plunger engagement pin 1118 opens the receiving space 1115 between the plunger engagement sleeve 1114 and the plunger engagement pin 1118 to allow one or more retaining members 368 of the plunger 326 to move distally from the receiving space 1115 (see Figure 31B).

[0346] When the plunger engagement mechanism 1112 is in the disengaged position or state, the syringe 300 can be pulled in the distal direction or the piston 1100 can be retracted in the proximal direction to remove the plunger 326 from the piston 1100. During the relative movement of the pistons 1100 toward the plunger 326 in one of the directions away from each other, the latches 374 of at least one retaining member 368 engage the plunger engagement post 1118 at the distal end of the locking groove 1127, such that each retaining member 368 is flexibly deflected in a radially outward direction (FIG. 31C). Continued movement of the piston 1100 relative to the plunger 326 allows the plunger 326 to be freely pulled apart from the piston 1100 (as shown in FIG. 31D) to allow the syringe 300 to be removed from the injector port.

[0347] Referring to Figure 31D, after the plunger 326 is removed from the piston 1100, the plunger engagement sleeve 1114 and the plunger engagement pin 1118 automatically rotate from the second position to the first position about the longitudinal axis 1120 due to the restoring force provided by the biasing member 1196. As the plunger engagement sleeve 1114 and the plunger engagement pin 1118 move to the first position, the guide pin 1139 is guided along one of the top surfaces 1179 within the opening 1162 of the plunger release sleeve 1158 due to the restoring force provided by the biasing member 1196.

[0348] Next, referring to Figures 32 to 35B, another embodiment of an injector assembly 2000 according to the present invention is shown. The injector assembly 2000 includes a housing 2002 that houses an automatic or electric fluid injector. The fluid injector is adapted to interface with and actuate one or more syringes, each of which can be independently filled with a medical fluid (such as a contrast agent, saline, or any desired medical fluid), as described above similarly with respect to Figures 1 or 3. For example, the injector housing 2002 is configured to accommodate syringes 2006a, 2006b, each containing a medical fluid.

[0349] As known in this art, syringes 2006a and 2006b are typically made of polypropylene or a similar material to have a specific minimum wall thickness. During certain procedures (such as angiography), syringes 2006a and 2006b may be subjected to pressures up to 1200 psi when used to inject fluid into a patient; therefore, the wall thickness and elasticity of the syringes are important to ensure that the syringes do not radially expand, rupture, dislodge from the injector, or leak. To further prevent syringes 2006a and 2006b from potentially expanding radially during high-pressure injection, respective pressure sheaths 2004a and 2004b are used to seal and retain syringes 2006a and 2006b. Pressure sheaths 2004a and 2004b are used to limit the radial expansion of the syringe barrel. That is, during an injection procedure, the outer wall of syringes 2006a and 2006b expands against the inner wall of one of the respective pressure sheaths 2004a and 2004b, thereby limiting the radial expansion of the outer wall of the syringe that would otherwise lead to rupture or leakage.

[0350] Pressure sleeves 2004a and 2004b may be separate components or may be formed as a single integral design. Pressure sleeves 2004a and 2004b are held on an injector head of housing 2002 via respective attachment interfaces 2010a and 2010b. Suitable non-limiting examples of pressure sleeves including syringe holding features for a CV injection procedure are described in International PCT Application PCT / US2020 / 049885 (incorporated herein by reference).

[0351] In addition to the radial forces acting on syringes 2006a, 2006b and pressure sheaths 2004a, 2004b, the significant axial movement of syringes 2006a, 2006b during high-pressure injection can also be attributed to the elastic properties of the structural components. For example, a single 150 ml syringe with a cross-sectional area of ​​1.6 in² at 1200 psi requires a force of 2400 psi to constrain the forward movement of the syringe. To limit this axial movement of syringes 2006a, 2006b, caps 2008a, 2008b can be used to partially encapsulate the distal ends of syringes 2006a, 2006b and retain them within the injector and pressure sheaths 2004a, 2004b during high-pressure injection. Caps 2008a and 2008b may have an opening formed on one of their distal ends to allow at least a portion of the neck 2009a and 2009b of one of the syringes 2006a and 2006b to protrude through it, thereby allowing syringes 2006a and 2006b to be connected to a fluid line leading to the patient.

[0352] Due to the axial forces applied to syringes 2006a and 2006b, it is desirable that the attachment interfaces between pressure sheaths 2004a and 2004b and the outer shell 2002, and / or between caps 2008a and 2008b and pressure sheaths 2004a and 2004b, have sufficient strength to resist axial movement or accidental detachment. However, while strength is critical, it is also important for an operator to be able to easily remove caps 2008a and 2008b and / or pressure sheaths 2004a and 2004b, as syringes 2006a and 2006b need to be removed or inserted. Therefore, it is desirable that the attachment interfaces between pressure sheaths 2004a and 2004b and the outer shell 2002 be sufficiently secure, yet allow for easy attachment and removal. Similarly, the connection interface between the caps 2008a and 2008b and the pressure sleeves 2004a and 2004b is expected to be secure, but allows for easy attachment and removal.

[0353] To achieve these desired properties, the attachment interfaces 2010a and 2010b of the pressure sleeves 2004a and 2004b may have connector features similar to those of the plunger 326 shown and described in Figures 6 to 8C, and the attachment interfaces 2020a and 2020b of the housing 2002 shown in Figure 32 may have connector features similar to those of various embodiments of the plunger engagement mechanism shown and described with reference to Figures 9 to 31D. Specifically, the attachment interfaces 2010a and 2010b may include one or more resilient flexible retaining members with a latch circumferentially positioned around an opening on the proximal end of the pressure sleeves 2004a and 2004b, similar to the resilient flexible retaining member 368 and latch 374 shown and described with reference to Figures 6 to 8C. Similarly, the attachment interfaces 2020a, 2020b of the housing 2002 may include one or more features similar to the plunger engagement sleeve and plunger engagement post shown and described with respect to Figures 9 to 31D.

[0354] In operation, attachment interfaces 2010a, 2010b and 2020a, 2020b are configured to interact in a manner substantially similar to the interaction between plunger 326 and plunger engagement mechanism, as shown and described in detail with respect to Figures 9 to 31D. That is, because attachment interfaces 2010a, 2010b are axially guided toward their respective attachment interfaces 2020a, 2020b, the respective attachment interfaces 2010a, 2010b and attachment interfaces 2020a, 2020b interact to secure pressure sleeves 2004a, 2004b to housing 2002. Next, one or more retaining members within attachment interfaces 2020a and 2020b (in some embodiments, which may protrude inward from the distal end of one of attachment interfaces 2020a and 2020b) are configured to engage a lip of one engagement ring 2022a and 2022b within each of attachment interfaces 2010a and 2010b to securely attach pressure sleeves 2004a and 2004b to housing 2002.

[0355] To allow pressure sleeves 2004a and 2004b to detach from housing 2002, pressure sleeves 2004a and 2004b can rotate relative to housing 2002 (together or separately). This rotation allows attachment interfaces 2010a and 2010b to interact with attachment interfaces 2020a and 2020b, similar to the interactions described above with respect to Figures 9 to 31D. This interaction is used to radially outward or inwardly push at least one retaining member such that at least one retaining member no longer engages with the corresponding structure on attachment interfaces 2010a and 2010b, at which point pressure sleeves 2004a and 2004b can be axially detached from housing 2002.

[0356] Alternatively, after insertion, the proximal end of the body of the syringes 2006a and 2006b within the pressure sleeves 2004a and 2004b can act like a plunger engagement pin to lock the corresponding flexible retaining member of the pressure sleeve in a corresponding locking groove or lip in the pressure sleeve port of the injector. Removing the syringes 2006a and 2006b from the pressure sleeves 2004a and 2004b (e.g., after completing an injection protocol) disengages the flexible retaining member of the pressure sleeve from the corresponding locking groove or lip in the pressure sleeve port to allow for removal of the pressure sleeve from the port.

[0357] According to an alternative embodiment of the invention, the structural details of the aforementioned attachment interfaces 2010a, 2010b and 2020a, 2020b can be reversed. That is, the attachment interfaces 2010a, 2010b of the pressure sleeves 2004a, 2004b may include, for example, at least one retaining member and corresponding features, while the attachment interfaces 2020a, 2020b may include features of the plunger engagement mechanism described herein with reference to Figures 9 to 31D.

[0358] Next, referring to Figures 34, 35A, and 35B, an alternative embodiment of the invention is shown. As discussed above with respect to Figures 32 and 33, caps 2008a and 2008b may be positioned generally around the distal end of one of their respective pressure sheaths 2004a and 2004b to axially hold the respective syringe therein. As shown in Figure 35A, a cap 2008 may have an attachment interface 2014 for attachment to a pressure sheath and an opening 2016 formed therein to allow a portion of the distal end of the syringe to extend through it.

[0359] To achieve a secure connection between pressure sleeves 2004a, 2004b and caps 2008a, 2008b, the respective interfaces between pressure sleeves 2004a, 2004b and caps 2008a, 2008b are advantageously configured such that they interact in a manner substantially similar to the interaction between various embodiments of plunger 326 and various embodiments of plunger engagement mechanisms shown and described in detail with respect to Figures 9 to 31D. As shown in Figure 33, pressure sleeves 2004a, 2004b may have respective attachment interfaces 2012a, 2012b at their distal ends for engagement with their respective caps 2008a, 2008b. Attachment interfaces 2012a, 2012b may include one or more plunger engagement mechanisms shown and described with respect to Figures 9 to 31D. Similarly, the attachment interface 2014 of the cap 2008 shown in Figure 35A may include one or more resiliently deflectable retaining members 368 together with a corresponding latch 374, as shown and described with reference to Figures 6 through 8C. The engagement between the attachment interfaces 2012a, 2012b of the pressure sleeves 2004a, 2004b and the attachment interface 2014 of the respective cap 2008 may be the same as or substantially similar to the engagement between the plunger 326 and the plunger engagement mechanism described above with respect to Figures 9 through 31D. In this way, the caps 2008a, 2008b can be securely engaged with and easily disengaged from the distal ends of the pressure sleeves 2004a, 2004b.

[0360] As an alternative to a cap 2008 that is separate from and surrounds a portion of a syringe, Figure 35B shows a syringe assembly 2030 having a syringe body 2032 and a cap 2036 integrated with the syringe body 2032. That is, the cap 2036 can be directly molded or formed together with the syringe body 2032. A neck portion 2034 extends from a distal surface of the cap 2036 to provide a connection point for a fluid line leading to the patient. An attachment interface 2038, similar to the attachment interface 2014 shown and described with respect to Figure 35A, is formed in the cap 2036. As described similarly above with respect to Figures 32 and 35A, the attachment interface 2038 may include features that interact with one of the corresponding attachment interfaces 2012a, 2012a of the pressure sheaths 2004a, 2004b. Furthermore, the engagement between the attachment interfaces 2012a and 2012b of the pressure sheaths 2004a and 2004b and the attachment interface 2038 of the respective syringe assembly 2030 may be the same as or substantially similar to the engagement described above with respect to Figures 9 to 31D.

[0361] According to an alternative embodiment of the invention, the structural details of the aforementioned attachment interfaces 2012a, 2012b, and 2014 can be reversed. That is, the attachment interfaces 2012a and 2012b of the pressure sleeves 2004a and 2004b may include, for example, at least one retaining member and corresponding features, while the attachment interface 2014 of each cap 2008 may include the corresponding features associated with the plunger engagement mechanism described herein with reference to Figures 9 to 31D. Similarly, the structural details of the aforementioned attachment interfaces 2012a, 2012b, and 2038 can be reversed.

[0362] Although shown and described as integrated with pressure sleeves 2004a and 2004b, the attachment interfaces 2010a, 2010b and 2012a, 2012b of pressure sleeves 2004a and 2004b, or both, may alternatively be formed by a separable assembly that can be attached to the proximal or distal end of pressure sleeves 2004a and 2004b. In this manner, a conventional pressure sleeve can be adapted to one or more separable attachment interfaces to enable secure interface with a suitable equipment housing, a cap similar to cap 2008, and / or a syringe assembly (similar to syringe assembly 2030 discussed above) having an integrated cap.

[0363] Although the invention has been described in detail based on what is currently considered to be the most practical and preferred embodiment for illustrative purposes, it should be understood that this detail is for that purpose only and the invention is not limited to the disclosed embodiments, but rather is intended to cover modifications and equivalent configurations. For example, it should be understood that the invention may be contemplated that, to the extent possible, one or more features of any embodiment may be combined with one or more features of any other embodiment.

[0364] 10: Fluid Injector System / Injector 11: User Interface 12: Syringe 13: Piston 14: Injector housing 15: Pressure sleeve 16: Syringe port 17: Fluid Path Set 17A: First fluid path 17B: Second Fluid Path 18: Syringe barrel 19A: Bulk fluid containers 19B: Bulk fluid containers 20: Proximal 21A: Bulk Fluid Path 21B: Bulk Fluid Path 23A: Bulk Fluid Valve 23B: Bulk Fluid Valve 26: Plunger 100: Dual-Injector Angiography Injector System / Injector 200: Controller 202: Busbar 204: Processor 206: Memory 208: Storage Components 210: Input Component 212: Output Component 214: Communication Interface 240: Upstream air detector 250: Air detection tube area 300: Syringe 315: Syringe longitudinal axis 318: Syringe barrel 319: Sidewall 320: Proximal 321: Outer surface 322: Nozzle 323: Inner surface 324: Remote 325: Internal volume 326: Plunger 327: Driven shoulder 329: Toothed portion 330: Insertion segment 331: Syringe holding component 332: Plunger body 334: Piston longitudinal axis 335: Droplet flange 336: Proximal 338: Remote 339: Circumferential sidewall 340: Inner cavity 342: Conical section 344: Cylindrical section 345: Highlighted Part 346: Truncated end 347a: Part 1 347b: Part Two 348: Molded hub / surface 350: Maintain ribs 352: Inner surface 356: Extension 357: Plunger Cap 358: Resilient Seal 360: Outer Surface 362: Circumferential groove 364: Outer surface 366: Sealing element 368: Retaining Components 369: Circular or angled release surface 370: First end 372: Second end 374:Latch 375: Circular or angled tachometer surface 377: Remote Surface 379: Proximal surface 380: Release the spur 382: Proximal 384: Pointed or angled guide surface 400: Piston 402: Electric motor / drive mechanism 404:Ontology 406: Piston head 412: Plunger engagement mechanism 414: Plunger Engagement Sleeve 415: Acceptance Space 416: Center opening 418: Plunger Engagement Column 420: Longitudinal piston axis / longitudinal axis 422: Actuator 424: Hollow body 426: Remote part / remote 428: Inner surface 430: Incline 432: Proximal portion / Proximal 434: Locking Rib 436: Inner surface 438: Longitudinal groove 439: Guide Selling 440: Remote stop 442: Outer surface 444: Toothed portion 446: Outer shell 448: Connecting components 450: Connector 452: Proximal portion 454: Remote portion 456: Highlighted Part 458: Plunger Release Sleeve 460: Cylindrical sidewall 462: Opening 463: Longitudinal surface 464: Vertical axis 466: Inclined surface 468: Remote 470: Proximal 472: Lamp / Shaft 474: Printed Circuit Board / Near End 476: Remote 478: Tapered end face 480: Seals 482: Vertical axis 484: Elastic and expandable component 486: Remote 488: Highlighted Part 490: Proximal 496: Offset component 500: Piston 512: Plunger Engagement Mechanism 514: Plunger Engagement Sleeve 515: Acceptance Space 516: Center Opening 518: Plunger Engagement Column 519: Proximal portion 520: Longitudinal piston axis / Piston longitudinal axis 521: Column section 523: Opening 524: Hollow body 525: Connector 526: Remote part / remote 527: Locking Groove 528: Inner surface 530: Incline 531: Vertical axis 532: Proximal portion / Proximal 533: Through hole 538: Longitudinal groove 539: Guide Selling 540: Remote stop 544: Tooth-shaped portion 558: Plunger Release Sleeve 560: Cylindrical sidewall 562: Opening 563: Longitudinal surface 564: Vertical axis 566: Inclined surface 568: Remote 570: Proximal 600: Piston 606: Piston head 612: Plunger Engagement Mechanism 614: Plunger Engagement Sleeve 615: Acceptance Space 616: Center Opening 618: Plunger Engagement Column 620: Longitudinal piston axis / longitudinal axis 624: Hollow body 626: Remote part / remote 630: Inclined surface / sloping surface 634: Locking Rib 637: Drive protrusion 642: Outer surface 644: Toothed portion 665: Trench 667: Longitudinal axis / outer surface 671: Rotating mechanism 672: Axis 673: Part One 674: Proximal 675: Part Two 676: Remote 678: Tapered end face 679: Highlighted Part 700: Piston 704:Ontology 705: Sensing component 706: Piston Head 707: Sales 709: Sensor 711: Spring 712: Plunger Engagement Mechanism 713: Proximal 714: Plunger Engagement Sleeve 715: Remote / Acceptance Space 716: Center Opening 717: First Step 718: Plunger Engagement Column 719: Second Step 720: Longitudinal piston axis / longitudinal axis 721: Column section 722: Actuator 723: Proximal portion 724: Hollow Body 726: Remote part / remote 728: Inner surface 729: Lock in the lip line 730: Incline 737: Radial Groove 767: Sales 800: Piston 803: Lamp 804:Ontology 805: Sensing component 806: Piston head 807: Sensing Sleeve 809: Sensor 812: Plunger Engagement Mechanism 813: Proximal 814: Plunger Engagement Sleeve 815: Remote / Acceptance Space 816: Center Opening 817: Spring 818: Plunger Engagement Column 820: Longitudinal axis / Longitudinal piston axis 822: Actuator 824: Hollow Body 826: Remote part / remote 828: Inner surface 834: Locking Rib 900: Piston 901: Rod 912: Plunger Engagement Mechanism 920: Piston head 940: Piston chamber 950: Locks in the lip line 960: Circular or angled distal surface 970: Circular or angled proximal surface 980: Locking component 990: Groove 1000: Piston 1006: Piston Head 1012: Plunger Engagement Mechanism 1014: Plunger Engagement Sleeve 1015: Acceptance Space 1016: Center Opening 1018: Plunger Engagement Column 1020: Longitudinal piston axis 1024: Hollow body 1026: Remote part / remote 1042: Outer surface 1044: Tooth-shaped portion 1065: Locking trench 1071: Rotating Mechanism 1072: Axis 1074: Proximal end 1076: Remote 1078: Conical end face 1100: Piston 1104:Ontology 1105: Sensing component 1106: Piston head 1107: Sales 1109: Sensor 1111: Spring 1112: Plunger engagement mechanism 1113: Proximal end 1114: Plunger Engagement Sleeve 1115: Acceptance Space 1116: Center Opening 1117: Remote 1118: Plunger Engagement Column 1119: Seals 1120: Longitudinal piston axis / longitudinal axis 1122: Actuator 1124: Hollow body 1126: Remote portion / remote 1127: Locking Groove 1128: Inner surface 1130: Incline 1132: Proximal / Proximal portion 1139: Guide Pin 1142: Outer surface 1144: Tooth-shaped portion 1145: Plunger release tooth 1146: Outer shell 1147: Remote 1149: Tip 1151: Remote 1152: Proximal portion 1153: Proximal end 1154: Remote portion 1156: Highlighted Part 1158: Plunger Release Sleeve 1159: Hollow body 1160: Cylindrical sidewall 1161: Inner cavity 1162: Opening 1163: Longitudinal surface 1164: Vertical axis 1166: Inclined surface 1168: Remote 1170: Proximal end 1172: Axis 1173: Lamp 1174: Remote 1175: Printed Circuit Board 1176: Proximal end 1178: Conical or round end face 1179: Top surface 1180: Seals 1196: Offset component 2000: Injector Assembly 2002: Outer shell 2004a: Pressure sleeve 2004b: Pressure Gland 2006a: Syringe 2006b: Syringe 2008: Hat 2008a: Hat 2008b: Hat 2009a: Neck 2009b: Neck 2010a: Attached Interface 2010b: Attached Interface 2012a: Attached Interface 2012b: Attached Interface 2014: Attached Interface 2016: Opening 2020a: Attached Interface 2020b: Attached Interface 2022a: Joining ring 2022b: Joining ring 2030: Syringe Assembly 2032: Injector Body 2034: Neck section 2036: Hat 2038: Attached Interface 2700: Piston 2714: Plunger Engagement Sleeve 2750: Flexible retaining member 2755: Keep the brakes on. 2774: Engaging flange / clutch 2784: Elastic and expandable components 2798: Locking Component 2799: Proximal surface A: Proximal direction A1: Distant direction B: Remote direction B1: Proximal direction C: Remote direction C1: Distant direction D: Proximal direction E: Remote direction F: Medical Fluid

Claims

1. A fluid injector system comprising: At least one reciprocating piston having a piston head; and a plunger engagement mechanism associated with the piston head and configured to engage a plunger connected to a syringe of the fluid injector system for reciprocatingly driving the plunger in the syringe due to movement of the at least one piston, the plunger engagement mechanism comprising: a plunger engagement sleeve having a hollow body; a plunger engagement post received within the hollow body of the plunger engagement sleeve; and an actuator operatively connected to one of the plunger engagement sleeve and the plunger engagement post, and configured to move the plunger engagement sleeve and the plunger engagement post between an engaged position and a disengaged position. In the engaged position, the plunger engagement post is positioned within the hollow body of the plunger engagement sleeve to capture at least one flexible retaining member associated with the plunger in a receiving space between the plunger engagement sleeve and the plunger engagement post, and in the disengaged position, the plunger engagement post is at least partially positioned outside the hollow body of the plunger engagement sleeve to allow flexible insertion or removal of the at least one flexible retaining member of the plunger from the receiving space.

2. The fluid injector system of claim 1, wherein the actuator is a rotary electric motor, a linear electric motor, a linear actuator, or a solenoid.

3. The fluid injector system as claimed in claim 1, wherein the actuator is manually operated.

4. The fluid injector system of claim 1, wherein the actuator has an engaged state for moving one of the plunger engagement sleeve and the plunger engagement pin to the engaged position and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement pin to the disengaged position.

5. The fluid injector system of claim 1, wherein the actuator is in the engaged state only during proximal movement of the at least one piston.

6. The fluid injector system of claim 1, further comprising at least one biasing element for moving the actuator from the engaged state to a disengaged state.

7. The fluid injector system of claim 1, wherein rotational movement of the actuator causes one of the plunger engagement sleeve and the plunger engagement post to move proximal or distal in a linear direction.

8. The fluid injector system of claim 1, wherein linear movement of the actuator causes one of the plunger engagement sleeve and the plunger engagement post to move proximal or distal in a linear direction.

9. The fluid injector system of claim 1, wherein the actuator is operatively connected to a controller configured to control the actuation of the actuator.

10. The fluid injector system of claim 1, wherein one of the plunger engagement sleeve and the plunger engagement post is linearly or rotationally movable relative to the piston, while the other of the plunger engagement sleeve and the plunger engagement post is stationary relative to the piston.

11. The fluid injector system of claim 1, wherein the plunger engagement post and the plunger engagement sleeve are linearly or rotationally movable relative to the piston.

12. The fluid injector system of claim 1, wherein the plunger engagement post includes a locking groove that projects radially inward from one outer surface of the plunger engagement post, and wherein the locking groove is configured to receive at least one latch on the at least one retaining member of the plunger.

13. The fluid injector system of claim 12, wherein a distal edge of the locking groove is configured to flexibly deflect the at least one retaining member of the plunger during axial movement of the plunger relative to the piston, so as to disengage the at least one latch of the at least one retaining member from the locking groove when one of the plunger engagement sleeve and the plunger engagement post moves to the disengaged position.

14. The fluid injector system of claim 1, wherein the plunger comprises: A plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal end and the distal end; and the at least one retaining member associated with the plunger body and extending from the proximal end of the plunger body.

15. The fluid injector system of claim 1, wherein the at least one retaining member comprises: A first end connected to a plunger body; a second end adjacent to the first end and radially and resiliently deflectable relative to the first end; and at least one stop located on the second end, wherein the at least one retaining member has an outer surface configured to engage a plunger engagement sleeve when the plunger engages with the piston, wherein the at least one retaining member has an inner surface configured to engage a plunger engagement post when the plunger engages with the piston, wherein the at least one stop is configured to securely engage a locking feature on one of the plunger engagement sleeve and the plunger engagement post to prevent axial movement of the plunger relative to the piston when the plunger engages with the piston, and wherein in an unlocked state of the plunger engagement mechanism, the at least one stop is configured to radially deflect the second end of the at least one retaining member after axial movement of the piston relative to the plunger due to the flexible interaction between the at least one stop and the locking feature.

16. The fluid injector system of claim 15, wherein the plunger is configured to engage the plunger engagement mechanism regardless of the angular orientation of the plunger relative to the piston of the fluid injector.

17. The fluid injector system of claim 15, wherein the at least one lever protrudes radially inward from the inner surface of the at least one retaining member in a direction toward a central longitudinal axis defined by the plunger body.

18. The fluid injector system of claim 17, wherein the at least one lever is configured to be received within the locking feature when the plunger and the piston are in the locked state, the locking feature being shaped as a locking groove protruding radially inward from one of the outer surfaces of the plunger engagement post.

19. The fluid injector system of claim 15, wherein the at least one lever protrudes radially outward from the outer surface of the at least one retaining member in a direction away from a central longitudinal axis defined by the plunger body.

20. The fluid injector system of claim 19, wherein the at least one lever is configured to be received within the locking feature, the locking feature being shaped as a locking groove protruding radially outward from one inner surface of the plunger engagement sleeve.

21. The fluid injector system of claim 15, wherein the at least one lever has a first circular proximal surface at one proximal end of the at least one lever configured to flexibly engage one of the plunger engagement sleeves and one of the plunger engagement pins during plunger engagement with the piston, and a second circular distal surface at one distal end of the at least one lever configured to flexibly engage one of the plunger engagement sleeves and one of the plunger engagement pins during plunger disengagement from the piston, at one proximal end of the locking feature.

Images