Systems and methods for syringe plunger engagement with an injector - Patents.com

Abstract

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

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 62 / 705,265, filed June 18, 2020, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates generally to a system including a front-loading syringe and / or pressure jacket for use with a fluid injector, and further 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. [Background technology]

[0003] In many medical diagnostic and therapeutic procedures, physicians inject one or more medical fluids into a patient. Numerous injector-actuated syringes and fluid injectors for pressurized injection of fluids, such as contrast solutions (often simply referred to as "contrast media"), flushing agents (such as saline or lactated Ringer's solution), and other medical fluids, have been developed for use in contrast 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 amount of one or more fluids at a preset flow rate.

[0004] Typically, a fluid injector has at least one drive member, such as, for example, a plunger or a piston, that connects to a syringe via a connection with an engagement feature in a proximal end wall of the syringe. The syringe may include a synthetic barrel having 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 or deliver fluid into or from the syringe barrel.

[0005] Various connection interfaces have been developed to facilitate engagement of the syringe plunger with the piston of the fluid injector. In some embodiments, a syringe having a retention feature is inserted into the syringe port of the fluid injector by aligning the syringe with a corresponding locking feature on the fluid injector. Such alignment also aligns the plunger in the syringe with the piston on the fluid injector so that the piston can engage the plunger and reciprocate within the syringe barrel to draw fluid into or deliver fluid to or from the syringe barrel. In another embodiment, upon initial engagement with the plunger, the piston is rotated in a clockwise or counterclockwise direction until the piston engages a catch on the plunger. In a further embodiment, the piston has a radially extendable pin that engages a lip on the plunger.

[0006] Many of the existing connection interfaces have structures that require complex piston heads with various sensor elements and active engagement structures. There is a need in the art for an improved connection interface that allows for simpler and easier engagement and disengagement of a syringe plunger with a piston of a fluid injector. There is a further need in the art to reduce or eliminate the need for an operator to rotationally align the syringe with the fluid injector prior to engagement of the syringe plunger with the piston of the fluid injector. Although various syringe connection interfaces and methods are known in the medical field, there continues to be a need for an improved connection interface between a syringe plunger and a piston of a fluid injector, as well as a method for engaging and disengaging a syringe plunger with a piston of a fluid injector. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Pat. No. 5,383,858 [Patent Document 2] U.S. Patent No. 7,553,294 [Patent Document 3] U.S. Pat. No. 7,666,169 [Patent Document 4] US Patent Application Publication No. 2014 / 0027009 [Patent Document 5] U.S. Pat. No. 8,945,051 [Patent Document 6] U.S. Patent No. 10,022,493 [Patent Document 7] U.S. Pat. No. 10,507,319 [Patent Document 8] U.S. Pat. No. 9,173,995 [Patent Document 9] U.S. Pat. No. 9,199,033 Summary of the Invention [Means for solving the problem]

[0008] There is a need in the art for an improved connection interface between a syringe plunger and a piston of a fluid injector that overcomes the shortcomings of the prior art. There is an additional need for a method of engaging and disengaging a syringe plunger from a piston of a fluid injector to allow for rapid loading or unloading of the syringe from the fluid injector.

[0009] According to some embodiments, a plunger for use with a syringe can include a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal and distal ends; and at least one retention member associated with the plunger body and extending proximally therefrom, the at least one retention member comprising a first end connected to the plunger body, a second end proximal to the first end and resiliently deflectable radially relative to the first end, and at least one catch on the second end, the at least one retention member can have an outer surface configured to engage a plunger engagement sleeve of a plunger engagement mechanism on a piston of a fluid injector system when the plunger can be in a locked condition with the piston. The at least one retaining member may have an inner surface configured to engage with a plunger engagement post of the plunger engagement mechanism when the plunger may be in a locked state with the piston, and the at least one catch may be configured to engage with a locking feature of one of the plunger engagement sleeve and the plunger engagement post when the plunger may be in a locked state with the piston to prevent axial movement of the plunger relative to the piston, and the at least one catch may be configured to radially deflect a second end of the at least one retaining member upon axial movement of the piston relative to the plunger in an unlocked state of the plunger from the piston due to engagement of the at least one catch with the locking feature of the plunger engagement sleeve and one of the plunger engagement post.

[0010] According to some embodiments, the at least one retention member may include a plurality of retention members spaced about the central longitudinal axis. The plurality of retention members may be equally spaced about the central longitudinal axis. The at least one retention member may extend proximally in a direction parallel to the central longitudinal axis or in a direction oblique to the central longitudinal axis. The at least one retention member may be linearly or curvilinearly continuous between the first end and the second end. The plunger may be configured to engage with the plunger engagement mechanism regardless of the angular orientation of the plunger relative to the piston of the fluid injector.

[0011] According to some embodiments, the at least one catch can have a first surface at a proximal end of the at least one catch configured to engage with a distal end of a locking feature of one of the plunger engagement sleeve and plunger engagement post during engagement of the plunger to the piston, and a second surface at a distal end of the at least one catch configured to engage with a proximal end of the locking feature of one of the plunger engagement sleeve and plunger engagement post during disengagement of the plunger from the piston.

[0012] According to some embodiments, the at least one catch can protrude radially inward from an inner surface of the at least one retaining member in a direction toward the central longitudinal axis or radially outward from an outer surface of the at least one retaining member in a direction away from the central longitudinal axis. The at least one catch can define a locking recess for receiving at least a portion of the plunger engagement mechanism when the plunger is connected to the piston. The at least one catch can protrude radially inward from an inner surface of the at least one retaining member in a direction toward the central longitudinal axis, and the at least one catch can be configured to be received within a locking feature that can be shaped as a locking groove protruding radially inward from an outer surface of the plunger engagement post when the plunger can be in a locked state with the piston.

[0013] According to some embodiments, the plunger body may have a conical portion at a distal end and a cylindrical portion at a proximal end. At least one retention member may protrude proximally from an inner surface of the conical portion. A plurality of release tabs may protrude radially inwardly from or proximally from the inner surface of the cylindrical portion, each of the plurality of release tabs configured to interact with the plunger engagement sleeve to cause release of the plunger from the piston upon rotation of the plunger about the central longitudinal axis. A proximal end of each of the plurality of release tabs may have a pointed guide surface.

[0014] According to some embodiments, the plunger cover can cover at least a portion of the distal face of the plunger body and can include a seal disposed about at least a portion of the circumferential sidewall of the plunger body.

[0015] According to some embodiments, the plunger may be configured to be slidably disposed within the barrel of the syringe.The plunger may be configured to reciprocate within the barrel of the syringe.

[0016] According to some embodiments, the fluid injector system includes at least one reciprocatable piston having a piston head; and a plunger engagement mechanism associated with the piston head and configured to engage a plunger of a syringe connected to the fluid injector system to reciprocate a plunger in the syringe by movement of the at least one piston, the plunger engagement mechanism including a plunger engagement sleeve having a hollow body, a plunger engagement post receivable in the hollow body of the plunger engagement sleeve, and a plunger engagement mechanism operably connected to one of the plunger engagement sleeve and the plunger engagement post ... sleeve having a hollow body and a plunger engagement post reciprocatingly engaging the plunger engagement mechanism. and an actuator configured to move one of the plunger engagement posts between an engaged position and a disengaged position, wherein in the engaged position, the plunger engagement post may be positioned within a hollow body of the plunger engagement sleeve to capture at least one resiliently flexible retaining member associated with the plunger within a receiving space between the plunger engagement collar and the plunger engagement post, and in the disengaged position, the plunger engagement post may be positioned at least partially 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.

[0017] 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 may be manually operated. The actuator may have an engaged state for moving one of the plunger engagement sleeve and the plunger engagement post to an engaged position and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement post to a disengaged position. The actuator may be automatically moved to the disengaged state during loss of power to the actuator. The actuator may be in the engaged state only during proximal movement of at least one piston. At least one biasing element may be provided for moving the actuator from the engaged state to the disengaged state.

[0018] According to some embodiments, rotational motion of the actuator can move one of the plunger engagement sleeve and the plunger engagement post proximally or distally in a linear direction. According to some embodiments, linear motion of the actuator can move one of the plunger engagement sleeve and the plunger engagement post proximally or distally in a linear direction. The actuator may be operably connected to a controller configured to control actuation of the actuator.

[0019] According to some embodiments, one of the plunger engagement sleeve and the plunger engagement post may be linearly or rotationally movable relative to the piston, and the other of the plunger engagement sleeve and the plunger engagement post may be stationary relative to the piston. The plunger engagement post and the plunger engagement collar may be linearly or rotationally movable relative to the piston.

[0020] According to some embodiments, the at least one sensor may 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. The plunger detection sensor may be configured to detect a presence of at least one retention member of the plunger in the receiving space between the plunger engagement collar and the plunger engagement post.

[0021] According to some embodiments, the hollow body of the plunger engagement sleeve may have an opening with a stepped inner diameter that decreases in a direction from the distal end of the plunger engagement sleeve to the proximal end of the plunger engagement sleeve. The plunger engagement post may include a locking groove that projects radially inward from an outer surface of the plunger engagement post, the locking groove may be configured to receive at least one catch on the at least one retention member of the plunger. A distal edge of the locking groove may be configured to flexibly bias the at least one retention member of the plunger during axial movement of the plunger relative to the piston to move the at least one catch of the at least one retention member out of engagement with the locking groove when one of the plunger engagement sleeve and the plunger engagement post may be moved to a disengaged position. The plunger engagement post may have a body with a stepped outer diameter that decreases in a direction from the distal end of the plunger engagement post to the proximal end of the plunger engagement post.

[0022] According to some embodiments, the plunger engagement collar may include a locking feature protruding radially inward from an inner surface of the plunger engagement collar. The locking feature may be configured to engage with at least one catch on the at least one retention member of the plunger when one of the plunger engagement sleeve and the plunger engagement post may be moved to an engaged position. The locking feature may be configured to flexibly bias the at least one retention member of the plunger during axial movement of the plunger relative to the piston to move the at least one catch of the at least one retention member out of engagement with the locking feature when one of the plunger engagement sleeve and the plunger engagement post may be moved to a disengaged position.

[0023] According to some embodiments, the fluid injector system may further include a syringe having a barrel having a barrel proximal end, a barrel distal end having an ejection nozzle, and a barrel sidewall extending between the barrel proximal end and the barrel distal end, and a plunger slidably disposed within the barrel and reciprocatable between the barrel proximal end and the barrel distal end.

[0024] According to some embodiments, the plunger can include a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal and distal ends, and at least one retention member associated with the plunger body and extending proximally therefrom.

[0025] According to some embodiments, the at least one retaining member may include a first end connected to the plunger body, a second end proximal to the first end and resiliently deflectable radially relative to the first end, and at least one catch on the second end, wherein the at least one retaining member may have an outer surface configured to engage with the plunger engagement sleeve when the plunger may be engaged with the piston, and the at least one retaining member may have an inner surface configured to engage with the plunger engagement post when the plunger may be engaged with the piston, and the at least one catch may be configured to engage with a locking feature of one of the plunger engagement sleeve and the plunger engagement post when the plunger may be engaged with the piston to prevent axial movement of the plunger relative to the piston, and the at least one catch may be configured to radially deflect the second end of the at least one retaining member upon axial movement of the piston relative to the plunger in a disengaged state of the plunger due to contact of the at least one catch with the locking feature.

[0026] According to some embodiments, the plunger may be configured to engage with the plunger engagement mechanism regardless of the angular orientation of the plunger relative to the piston of the fluid injector. The at least one catch may protrude radially inward from an inner surface of the at least one retaining member in a direction toward the central longitudinal axis. The at least one catch may be configured to be received within a locking feature, which may be shaped as a locking groove protruding radially inward from an outer surface of the plunger engagement post, when the plunger may be in a locked condition with the piston.

[0027] According to some embodiments, the at least one catch can protrude radially inward from an 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 catch can protrude radially outward from an outer surface of the at least one retaining member in a direction away from the central longitudinal axis.

[0028] According to some embodiments, the plunger body may have a conical portion at a distal end and a cylindrical portion at a proximal end. At least one retention member may protrude proximally from an inner surface of the conical portion. A plurality of release tabs may protrude radially inward from an inner surface of the cylindrical portion, each of the plurality of release tabs being configured to interact with the plunger engagement sleeve to cause release of the plunger from the piston upon rotation of the plunger about the central longitudinal axis. A proximal end of each of the plurality of release tabs may have a pointed guide surface.

[0029] According to some embodiments, a fluid injector system may include at least one reciprocatable piston having a piston head; and a plunger engagement mechanism associated with the piston head and configured to engage a plunger of a syringe connected to the fluid injector system to reciprocate the plunger within the syringe by movement of the at least one piston, the plunger engagement mechanism comprising a plunger engagement sleeve having a hollow body having a longitudinal axis; and a plunger engagement post receivable 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 may be rotatable about the longitudinal axis between a first position and a second position, and the plunger engagement post may be axially movable along the longitudinal axis from the engaged position to the disengaged position via rotation of the plunger engagement sleeve.

[0030] According to some embodiments, the plunger engagement post may be axially movable from a proximal end of the piston toward a distal end of the piston. The plunger release sleeve may include a plurality of plunger release teeth projecting radially outward from an outer surface of the hollow body. The plurality of plunger release teeth may be configured to engage a plurality of release tabs on the plunger such that rotation of the plunger about the plunger longitudinal axis causes rotation of the plunger engagement sleeve about the longitudinal axis.

[0031] According to some embodiments, the plunger release sleeve can surround at least a portion of the plunger engagement sleeve, and the plunger release sleeve can be configured to rotate about the longitudinal axis with rotation of the plunger engagement sleeve. The plunger release sleeve can include an opening having an inclined surface that can be inclined relative to the direction of the longitudinal axis in a direction from the distal end of the plunger release sleeve toward the proximal end of the plunger release sleeve.

[0032] According to some embodiments, the plunger engagement post may have a guide pin extending in a direction perpendicular to the longitudinal axis, and the guide pin may be received in an opening in the plunger release sleeve. Rotation of the plunger engagement sleeve may cause a corresponding rotation of the plunger release sleeve. The guide pin is guided along the ramp from a proximal end to a distal end of the ramp, thereby moving the plunger engagement post from an engaged position to a disengaged position.

[0033] According to some embodiments, a biasing member may be operably connected to the plunger engagement sleeve and the plunger engagement post. The biasing member may be configured to bias the plunger engagement sleeve toward the first position.

[0034] According to some embodiments, the 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 may be disposed within a hollow body of the plunger engagement sleeve and may be configured to capture at least one resiliently flexible retention member associated with the plunger within a receiving space between the plunger engagement collar and the plunger engagement post. In the disengaged position, the plunger engagement post may be disposed at least partially outside the hollow body of the plunger engagement sleeve to permit flexible insertion or removal of the at least one resiliently flexible retention member of the plunger from the receiving space.

[0035] 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 may be manually operated. The actuator may have an engaged state for moving one of the plunger engagement sleeve and the plunger engagement post to an engaged position and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement post to a disengaged position. The actuator may be automatically moved to the disengaged state during loss of power to the actuator. The actuator may be in the engaged state only during proximal movement of at least one piston.

[0036] According to some embodiments, the at least one biasing element is configured to move the actuator from an engaged state to a disengaged state. Rotational or linear motion of the actuator moves one of the plunger engagement sleeve and the plunger engagement post proximally or distally in a linear direction. The actuator may be operably connected to a controller configured to control actuation of the actuator.

[0037] According to some embodiments, the at least one sensor may 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. The plunger detection sensor may be configured to detect a presence of at least one retention member of the plunger in the receiving space between the plunger engagement collar and the plunger engagement post.

[0038] According to some embodiments, the hollow body of the plunger engagement sleeve may have an opening with a stepped inner diameter that decreases in a direction from the distal end of the plunger engagement sleeve to the proximal end of the plunger engagement sleeve. The plunger engagement post may include a locking groove that projects radially inward from an outer surface of the plunger engagement post, the locking groove may be configured to receive at least one catch on the at least one retention member of the plunger. A distal edge of the locking groove may be configured to flexibly bias the at least one retention member of the plunger during axial movement of the plunger relative to the piston to move the at least one catch of the at least one retention member out of engagement with the locking groove when one of the plunger engagement sleeve and the plunger engagement post may be moved to a disengaged position.

[0039] According to some embodiments, the fluid injector system may further include a syringe having a barrel having a barrel proximal end, a barrel distal end having an ejection nozzle, and a barrel sidewall extending between the barrel proximal end and the barrel distal end, and a plunger slidably disposed within the barrel and reciprocatable between the barrel proximal end and the barrel distal end.

[0040] According to some embodiments, the plunger can include a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal and distal ends, and at least one retention member associated with the plunger body and extending proximally therefrom.

[0041] According to some embodiments, the at least one retaining member may include a first end connected to the plunger body, a second end proximal to the first end and resiliently deflectable radially relative to the first end, and at least one catch on the second end, wherein the at least one retaining member may have an outer surface configured to engage with the plunger engagement sleeve when the plunger may be engaged with the piston, and the at least one retaining member may have an inner surface configured to engage with the plunger engagement post when the plunger may be engaged with the piston, and the at least one catch may be configured to engage with a locking feature of one of the plunger engagement sleeve and the plunger engagement post when the plunger may be engaged with the piston to prevent axial movement of the plunger relative to the piston, and the at least one catch may be configured to radially deflect the second end of the at least one retaining member upon axial movement of the piston relative to the plunger in a disengaged state of the plunger due to contact of the at least one catch with the locking feature.

[0042] According to some embodiments, the plunger may be configured to engage with the plunger engagement feature regardless of the angular orientation of the plunger relative to the piston of the fluid injector.

[0043] According to some embodiments, the at least one catch may protrude radially inward from an inner surface of the at least one retaining member in a direction toward the central longitudinal axis, and the at least one catch may be configured to be received within a locking feature, which may be shaped as a locking groove protruding radially inward from an outer surface of the plunger engagement post, when the plunger may be in a locked state with the piston.

[0044] According to some embodiments, the at least one catch may project radially inward from an inner surface of the at least one retaining member in a direction toward the central longitudinal axis, or the at least one catch may project radially outward from an outer surface of the at least one retaining member in a direction away from the central longitudinal axis. The at least one catch may define a locking recess for receiving at least a portion of the plunger engagement mechanism when the plunger may be connected to the piston.

[0045] According to some embodiments, the plunger body may have a conical portion at a distal end and a cylindrical portion at a proximal end. At least one retention member may protrude proximally from an inner surface of the conical portion. A plurality of release tabs may protrude radially inwardly from or proximally from the inner surface of the cylindrical portion, each of the plurality of release tabs configured to interact with the plunger engagement sleeve to cause release of the plunger from the piston upon rotation of the plunger about the central longitudinal axis. A proximal end of each of the plurality of release tabs may have a pointed guide surface.

[0046] Further embodiments or aspects of the present disclosure are described in the following numbered clauses:

[0047] 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 and distal ends; and at least one retention member associated with the plunger body and extending proximally therefrom, the at least one retention member comprising a first end connected to the plunger body, a second end proximal to the first end and radially resiliently deflectable relative to the first end, and at least one catch at the second end, the at least one retention member having an outer surface configured to engage a plunger engagement sleeve of a plunger engagement mechanism on a piston of a fluid injector system when the plunger is in a locked condition with the piston. the at least one retaining member has an inner surface configured to engage with a plunger engagement post of the plunger engagement mechanism when the plunger is in an locked state with the piston, the at least one catch is configured to engage with one of the locking features of the plunger engagement sleeve and the plunger engagement post when the plunger is in an locked state with the piston to prevent axial movement of the plunger relative to the piston, and the at least one catch is configured to radially deflect a second end of the at least one retaining member upon axial movement of the piston relative to the plunger in an unlocked state of the plunger from the piston due to engagement of the at least one catch with the one of the locking features of the plunger engagement sleeve and the plunger engagement post.

[0048] Clause 2. The plunger of clause 1, wherein the at least one retaining member comprises a plurality of retaining members spaced apart about the central longitudinal axis.

[0049] Clause 3. The plunger of clause 2, wherein the plurality of retention members are equally spaced about the central longitudinal axis.

[0050] Clause 4. A plunger described in any one of clauses 1 to 3, wherein at least one retention member extends proximally in a direction parallel to the central longitudinal axis.

[0051] Clause 5. A plunger described in any one of clauses 1 to 3, wherein at least one retention member extends proximally in a direction oblique to the longitudinal axis.

[0052] Clause 6. A plunger as described in any one of clauses 1 to 5, wherein at least one retaining member is linearly continuous between the first end and the second end.

[0053] Clause 7. A plunger as described in any one of clauses 1 to 5, wherein at least one retaining member is curvilinearly continuous between the first end and the second end.

[0054] Clause 8. A plunger as described in any one of clauses 1 to 7, wherein the plunger is configured to engage with the plunger engagement mechanism regardless of angular orientation of the plunger relative to the piston of the fluid injector.

[0055] Clause 9. A plunger as described in any one of clauses 1 to 8, wherein the at least one catch has a first surface at a proximal end of the at least one catch configured to engage with a distal end of one of the locking features of the plunger engagement sleeve and the plunger engagement post during engagement of the plunger to the piston, and a second surface at a distal end of the at least one catch configured to engage with a proximal end of the locking feature of the plunger engagement sleeve and one of the locking features of the plunger engagement post during disengagement of the plunger from the piston.

[0056] Clause 10. A plunger as described in any one of clauses 1 to 9, wherein at least one catch protrudes radially inwardly from an inner surface of the at least one retaining member in a direction toward the central longitudinal axis.

[0057] Clause 11. A plunger as described in any one of clauses 1 to 10, wherein at least one catch projects radially outward from an outer surface of the at least one retaining member in a direction away from the central longitudinal axis.

[0058] Clause 12. A plunger as described in any one of clauses 1 to 11, wherein the at least one catch defines a locking recess for receiving at least a portion of the plunger engagement mechanism when the plunger is connected to the piston.

[0059] Clause 13. A plunger as described in any one of clauses 1 to 12, wherein at least one catch protrudes radially inward from an inner surface of at least one retaining member in a direction toward the central longitudinal axis, and wherein the at least one catch is configured to be received within a locking feature, which may be shaped as a locking groove protruding radially inward from an outer surface of the plunger engagement post, when the plunger is in an engaged state with the piston.

[0060] Clause 14. A plunger according to any one of clauses 1 to 13, wherein the plunger body has a conical portion at a distal end and a cylindrical portion at a proximal end.

[0061] Clause 15. The plunger of clause 14, wherein the at least one retention member protrudes proximally from an inner surface of the cone-shaped portion.

[0062] Clause 16. The plunger of clause 14 or 15, further comprising a plurality of release tabs projecting radially inward from the inner surface of the cylindrical portion or proximally from the inner surface of the cylindrical portion, each of the plurality of release tabs configured to interact with the plunger engagement sleeve to cause release of the plunger from the piston upon rotation of the plunger about the central longitudinal axis.

[0063] Clause 17. The plunger of clause 16, wherein a proximal end of each of the plurality of release tabs has a pointed guide surface.

[0064] Clause 18. A plunger as described in any one of clauses 1 to 17, further comprising a plunger cover covering at least a portion of a distal face of the plunger body and comprising a seal provided around at least a portion of a circumferential side wall of the plunger body.

[0065] Clause 19. A plunger according to any one of clauses 1 to 18, wherein the plunger is configured to be slidably disposed within the barrel of the syringe.

[0066] Clause 20. The plunger of clause 19, wherein the plunger is configured to reciprocate within the barrel of the syringe.

[0067] Clause 21. A fluid injector system, comprising: at least one reciprocatable piston having a piston head; and a plunger engagement mechanism associated with the piston head and configured to engage a plunger of a syringe connected to the fluid injector system to reciprocate a plunger in the syringe by movement of the at least one piston, the plunger engagement mechanism comprising a plunger engagement sleeve having a hollow body, a plunger engagement post receivable in the hollow body of the plunger engagement sleeve, and a plunger engagement post operably connected to one of the plunger engagement sleeve and the plunger engagement post, the plunger engagement mechanism including a plunger engagement sleeve having a hollow body and a plunger engagement post receivable in the hollow body of the plunger engagement sleeve, the plunger engagement mechanism being operably connected to one of the plunger engagement sleeve and the plunger engagement post. and an actuator configured to move a plunger engagement mechanism comprising: a plunger engagement collar configured to move a plunger engagement post between an engaged position and a disengaged position, wherein in the engaged position, the plunger engagement post is disposed within a hollow body of the plunger engagement sleeve to capture at least one resiliently flexible retention member associated with the plunger within a receiving space between the plunger engagement collar and the plunger engagement post, and in the disengaged position, the plunger engagement post is disposed at least partially outside the hollow body of the plunger engagement sleeve to allow flexible insertion or removal of the at least one resiliently flexible retention member of the plunger from the receiving space.

[0068] 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.

[0069] Clause 23. The fluid injector system of clause 21, wherein the actuator is manually operated.

[0070] Clause 24. A fluid injector system as described in any one of clauses 21 to 23, wherein the actuator has an engaged state for moving one of the plunger engagement sleeve and the plunger engagement post to an engaged position, and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement post to a disengaged position.

[0071] Clause 25. A fluid infuser system as described in any one of clauses 21 to 24, wherein the actuator is dynamically moved to a disengaged state upon loss of power to the actuator.

[0072] Clause 26. A fluid injector system according to any one of clauses 21 to 25, wherein the actuator is in an engaged state only during proximal movement of at least one piston.

[0073] Clause 27. The fluid injector system of any one of clauses 21 to 26, further comprising at least one biasing element for moving the actuator from the engaged state to the disengaged state.

[0074] Clause 28. A fluid injector system as described in any one 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 proximally or distally in a linear direction.

[0075] Clause 29. A fluid injector system as described in any one of clauses 21 to 28, wherein linear motion of the actuator moves one of the plunger engagement sleeve and the plunger engagement post proximally or distally in a linear direction.

[0076] Clause 30. A fluid injector system as described in any one of clauses 21 to 29, wherein the actuator is operably connected to a controller configured to control operation of the actuator.

[0077] Clause 31. A fluid injector system as described in any one of clauses 21 to 30, wherein one of the plunger engagement sleeve and the plunger engagement post is movable linearly or rotationally relative to the piston, and the other of the plunger engagement sleeve and the plunger engagement post is stationary relative to the piston.

[0078] Clause 32. A fluid injector system as described in any one of clauses 21 to 31, wherein the plunger engagement post and the plunger engagement collar are linearly or rotationally movable relative to the piston.

[0079] Clause 33. The fluid injector system of any one of clauses 21 to 32, further comprising at least one sensor configured to detect the position of at least one of the plunger engagement collar and the plunger engagement post between an engaged position and a disengaged position.

[0080] Clause 34. A fluid injector system as described in any one 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.

[0081] Clause 35. A fluid injector system as described in any one of clauses 21 to 34, wherein the hollow body of the plunger engaging sleeve has an opening with a stepped inner diameter that decreases in a direction from the distal end of the plunger engaging sleeve to the proximal end of the plunger engaging sleeve.

[0082] Clause 36. A fluid injector system as described in any one of clauses 21 to 35, wherein the plunger engagement post has a locking groove protruding radially inward from an outer surface of the plunger engagement post, the locking groove being configured to receive at least one catch on at least one retaining member of the plunger.

[0083] Clause 37. The fluid injector system of clause 36, wherein a distal edge of the locking groove is configured to flexibly deflect at least one retaining member of the plunger during axial movement of the plunger relative to the piston to move at least one catch of the at least one retaining member out of engagement with the locking groove when one of the plunger engagement sleeve and the plunger engagement post is moved to a disengaged position.

[0084] Clause 38. A fluid injector system as described in any one of clauses 21 to 37, wherein the plunger engagement post has a body having a stepped outer diameter that decreases in a direction from the distal end of the plunger engagement post to the proximal end of the plunger engagement post.

[0085] Clause 39. A fluid injector system as described in any one of clauses 21 to 38, wherein the plunger engagement collar includes a locking feature protruding radially inward from an inner surface of the plunger engagement collar, the locking feature being configured to engage with at least one catch on at least one retaining member of the plunger when one of the plunger engagement sleeve and the plunger engagement post is moved to an engaged position.

[0086] Clause 40. The fluid injector system of clause 39, wherein the locking feature is configured to flexibly deflect at least one retaining member of the plunger during axial movement of the plunger relative to the piston to move at least one catch of the at least one retaining member out of engagement with the locking feature when one of the plunger engagement sleeve and the plunger engagement post is moved to a disengaged position.

[0087] Clause 41. A fluid injector system as described in any one of clauses 21 to 39, further comprising a syringe comprising a barrel having a barrel proximal end, a barrel distal end having an ejection nozzle, and a barrel sidewall extending between the barrel proximal end and the barrel distal end, and a plunger slidably disposed within the barrel and reciprocatable between the barrel proximal end and the barrel distal end.

[0088] Clause 42. The fluid injector system described in Clause 41, 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 and distal ends, and at least one retention member associated with the plunger body and extending proximally therefrom.

[0089] Clause 43. The fluid injector system of clause 41 or 42, wherein the at least one retaining member comprises a first end connected to the plunger body, a second end proximal to the first end and resiliently deflectable radially relative to the first end, and at least one catch on the second end, wherein the at least one retaining member has an outer surface configured to engage with the plunger engagement sleeve when the plunger is engaged with the piston, and the at least one retaining member has an inner surface configured to engage with the plunger engagement post when the plunger is engaged with the piston, and the at least one catch is configured to engage with a locking feature of one of the plunger engagement sleeve and the plunger engagement post when the plunger is engaged with the piston to prevent axial movement of the plunger relative to the piston, and the at least one catch is configured to radially deflect the second end of the at least one retaining member upon axial movement of the piston relative to the plunger in a disengaged state of the plunger due to contact of the at least one catch with the locking feature.

[0090] Clause 44. A fluid injector system according to any one of clauses 41 to 43, wherein the plunger is configured to engage with the plunger engagement mechanism regardless of the angular orientation of the plunger relative to the piston of the fluid injector.

[0091] Clause 45. A fluid injector system as described in any one of clauses 41 to 44, wherein at least one catch protrudes radially inward from an inner surface of at least one retaining member in a direction toward the central longitudinal axis, and the at least one catch is configured to be received within a locking feature, which may be shaped as a locking groove protruding radially inward from an outer surface of the plunger engagement post, when the plunger is in an engaged state with the piston.

[0092] Clause 46. A fluid injector system as described in any one of clauses 41 to 45, wherein at least one catch protrudes radially inward from an inner surface of at least one retaining member in a direction toward the central longitudinal axis, or at least one catch protrudes radially outward from an outer surface of at least one retaining member in a direction away from the central longitudinal axis.

[0093] Clause 47. A fluid injector system as described in any one of clauses 41 to 46, wherein the plunger body has a conical portion at a distal end and a cylindrical portion at a proximal end.

[0094] Clause 48. The fluid injector system of clause 47, wherein at least one retention member protrudes proximally from an inner surface of the cone-shaped portion.

[0095] Clause 49. The fluid injector system of clause 47 or 48, further comprising a plurality of release tabs protruding radially inward from an inner surface of the cylindrical portion, each of the plurality of release tabs configured to interact with the plunger engagement sleeve to cause release of the plunger from the piston upon rotation of the plunger about the central longitudinal axis.

[0096] Clause 50. The fluid infuser system of clause 49, wherein a proximal end of each of the plurality of release tabs has a pointed guide surface.

[0097] Clause 51. A fluid injector system comprising: at least one reciprocatable piston having a piston head; and a plunger engagement mechanism associated with the piston head and configured to engage a plunger of a syringe connected to the fluid injector system to reciprocate the plunger within the syringe by movement of the at least one piston, the plunger engagement mechanism comprising a plunger engagement sleeve having a hollow body having a longitudinal axis; and a plunger engagement post receivable 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, the plunger engagement sleeve being rotatable about the longitudinal axis between a first position and a second position, and the plunger engagement post being axially movable along the longitudinal axis from the engaged position to the disengaged position via rotation of the plunger engagement sleeve.

[0098] Clause 52. The fluid injector system of clause 51, wherein the plunger engagement post is axially movable from a proximal end of the piston toward a distal end of the piston.

[0099] Clause 53. The fluid injector system of clause 51 or 52, wherein the plunger release sleeve includes a plurality of plunger release teeth projecting radially outward from an outer surface of the hollow body.

[0100] Clause 54. The fluid injector system of clause 53, wherein the plurality of plunger release teeth are configured to engage with a plurality of release tabs on the plunger such that rotation of the plunger about the plunger longitudinal axis causes rotation of the plunger engagement sleeve about the longitudinal axis.

[0101] Clause 55. A fluid injector system as described in any one of clauses 51 to 54, further comprising a plunger release sleeve surrounding at least a portion of the plunger engagement sleeve, the plunger release sleeve configured to rotate about the longitudinal axis with rotation of the plunger engagement sleeve.

[0102] Clause 56. A fluid injector system as described in any one of clauses 51 to 55, wherein the plunger release sleeve has an opening having an inclined surface inclined relative to the longitudinal axis in a direction from the distal end of the plunger release sleeve toward the proximal end of the plunger release sleeve.

[0103] 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, the guide pin being received in an opening in the plunger release sleeve.

[0104] Clause 58. The fluid injector system of clause 57, wherein rotation of the plunger engagement sleeve causes corresponding rotation of the plunger release sleeve, and the guide pin is guided along the ramp from a proximal end toward a distal end of the ramp, thereby moving the plunger engagement post from an engaged position to a disengaged position.

[0105] Clause 59. The fluid injector system of any one of clauses 51 to 58, further comprising a biasing member operably connected to the plunger engagement sleeve and the plunger engagement post.

[0106] Clause 60. The fluid injector system of clause 59, wherein the biasing member is configured to bias the plunger engagement sleeve to the first position.

[0107] Clause 61. The fluid injector system of any one 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 engaged position and the disengaged position.

[0108] Clause 62. A fluid injector system as described in Clause 61, wherein in the engaged position, the plunger engagement post is disposed within a hollow body of the plunger engagement sleeve and configured to capture at least one resiliently flexible retaining member associated with the plunger within a receiving space between the plunger engagement collar and the plunger engagement post, and in the disengaged position, the plunger engagement post is disposed at least partially 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.

[0109] 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.

[0110] Clause 64. A fluid injector system as described in any one of clauses 61 to 63, wherein the actuator is manually operated.

[0111] Clause 65. A fluid injector system as described in 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 post to an engaged position, and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement post to a disengaged position.

[0112] Clause 66. A fluid injector system according to any one of clauses 61 to 65, wherein the actuator is dynamically moved to a disengaged state upon loss of power to the actuator.

[0113] Clause 67. A fluid injector system according to any one of clauses 61 to 66, wherein the actuator is in an engaged state only during proximal movement of at least one piston.

[0114] Clause 68. The fluid injector system of any one of clauses 61 to 67, further comprising at least one biasing element for moving the actuator from the engaged state to the disengaged state.

[0115] Clause 69. A fluid injector system as described in any one 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 proximally or distally in a linear direction.

[0116] Clause 70. A fluid injector system as described in any one of clauses 61 to 69, wherein linear motion of the actuator moves one of the plunger engagement sleeve and the plunger engagement post proximally or distally in a linear direction.

[0117] Clause 71. A fluid injector system according to any one of clauses 61 to 70, wherein the actuator is operably connected to a controller configured to control operation of the actuator.

[0118] Clause 72. The fluid injector system of any one of clauses 51 to 71, further comprising at least one sensor configured to detect a position of at least one of the plunger engagement collar and the plunger engagement post between an engaged position and a disengaged position.

[0119] Clause 73. A fluid injector system as described in any one of clauses 51 to 72, 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.

[0120] Clause 74. A fluid injector system as described in any one of clauses 51 to 73, wherein the hollow body of the plunger engaging sleeve has an opening with a stepped inner diameter that decreases in a direction from the distal end of the plunger engaging sleeve to the proximal end of the plunger engaging sleeve.

[0121] Clause 75. A fluid injector system as described in any one of clauses 51 to 74, wherein the plunger engagement post has a locking groove protruding radially inward from an outer surface of the plunger engagement post, the locking groove being configured to receive at least one catch on at least one retaining member of the plunger.

[0122] Clause 76. The fluid injector system of clause 75, wherein the distal edge of the locking groove is configured to flexibly deflect at least one retaining member of the plunger during axial movement of the plunger relative to the piston to move at least one catch of the at least one retaining member out of engagement with the locking groove when one of the plunger engagement sleeve and the plunger engagement post is moved to a disengaged position.

[0123] Clause 77. A fluid injector system as described in any one of clauses 51 to 76, further comprising a syringe comprising a barrel having a barrel proximal end, a barrel distal end having an ejection nozzle, and a barrel sidewall extending between the barrel proximal end and the barrel distal end, and a plunger slidably disposed within the barrel and reciprocatable between the barrel proximal end and the barrel distal end.

[0124] Clause 78. The fluid injector system described in Clause 77, 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 and distal ends, and at least one retention member associated with the plunger body and extending proximally therefrom.

[0125] Clause 79. The fluid injector system of clause 77 or 78, wherein the at least one retaining member comprises a first end connected to the plunger body, a second end proximal to the first end and resiliently deflectable radially relative to the first end, and at least one catch on the second end, wherein the at least one retaining member has an outer surface configured to engage with the plunger engagement sleeve when the plunger is engaged with the piston, and the at least one retaining member has an inner surface configured to engage with the plunger engagement post when the plunger is engaged with the piston, and the at least one catch is configured to engage with a locking feature of one of the plunger engagement sleeve and the plunger engagement post when the plunger is engaged with the piston to prevent axial movement of the plunger relative to the piston, and the at least one catch is configured to radially deflect the second end of the at least one retaining member upon axial movement of the piston relative to the plunger in a disengaged state of the plunger due to contact of the at least one catch with the locking feature.

[0126] Clause 80. The fluid injector system of any one of clauses 77 to 79, wherein the plunger is configured to engage with the plunger engagement mechanism regardless of angular orientation of the plunger relative to the piston of the fluid injector.

[0127] Clause 81. A fluid injector system as described in any one of clauses 77 to 80, wherein at least one catch protrudes radially inward from an inner surface of at least one retaining member in a direction toward the central longitudinal axis, and the at least one catch is configured to be received within a locking feature, which may be shaped as a locking groove protruding radially inward from an outer surface of the plunger engagement post, when the plunger is in an engaged state with the piston.

[0128] Clause 82. A fluid injector system as described in any one of clauses 77 to 81, wherein at least one catch protrudes radially inward from an inner surface of at least one retaining member in a direction toward the central longitudinal axis, or at least one catch protrudes radially outward from an outer surface of at least one retaining member in a direction away from the central longitudinal axis.

[0129] Clause 83. A fluid injector system as described in any one of clauses 77 to 82, wherein at least one catch defines a locking recess for receiving at least a portion of the plunger engagement mechanism when the plunger is connected to the piston.

[0130] Clause 84. A fluid injector system as described in any one of clauses 77 to 83, wherein the plunger body has a conical portion at a distal end and a cylindrical portion at a proximal end.

[0131] Clause 85. The fluid injector system of clause 84, wherein at least one retention member protrudes proximally from an inner surface of the cone-shaped portion.

[0132] Clause 86. The fluid injector system of clause 84 or 85, further comprising a plurality of release tabs protruding radially inward from the inner surface of the cylindrical portion or proximally from the inner surface of the cylindrical portion, each of the plurality of release tabs being configured to interact with the plunger engagement sleeve to cause release of the plunger from the piston upon rotation of the plunger about the central longitudinal axis.

[0133] Clause 87. The fluid injector system of clause 86, wherein a proximal end of each of the plurality of release tabs has a pointed guide surface.

[0134] These and other features and characteristics of the syringe, syringe plunger, pressure jacket, and system having the syringe and / or syringe plunger, and the method of operation and function of the associated elements of structure and combination of parts and manufacturing economies will become more apparent from a consideration of the following description and appended claims with reference to the accompanying drawings, all of which form a part of this specification, and in which like reference numerals designate corresponding parts in the various views, It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only. [Brief description of the drawings]

[0135] [Figure 1] FIG. 1 is a perspective view of a fluid injector system according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram of the fluid infuser system of FIG. 1. [Diagram 3] 1 is a perspective view of a fluid injector system according to another embodiment of the present disclosure. [Figure 4] FIG. 2 is a schematic diagram of a controller for a fluid injector system according to one embodiment of the present disclosure. [Figure 5A] FIG. 1 is a perspective view of a syringe according to an embodiment of the present disclosure. [Figure 5B] FIG. 5B is a cross-sectional view of the syringe of FIG. 5A showing the plunger disposed within the barrel of the syringe. [Figure 6] FIG. 2 is an exploded perspective view of a plunger according to one embodiment of the present disclosure. [Figure 7] FIG. 7 is a cross-sectional perspective view of the support ring of the plunger of FIG. [Figure 8A] FIG. 13 is a cross-sectional perspective view of a support ring of a plunger according to another embodiment of the present disclosure. [Figure 8B] FIG. 13 is a cross-sectional perspective view of a support ring of a plunger according to another embodiment of the present disclosure. [Figure 8C] FIG. 13 is a cross-sectional perspective view of a support ring of a plunger according to another embodiment of the present disclosure. [Figure 9] FIG. 13 is a cross-sectional perspective view of a piston of a plunger engagement mechanism according to one embodiment of the present disclosure. [Figure 10A] 10 is a perspective view of a plunger engagement sleeve of the plunger engagement mechanism shown in FIG. 9. [Figure 10B] FIG. 10B is a cross-sectional view of the plunger engagement sleeve shown in FIG. 10A. [Figure 11A] 10 is a perspective view of the actuator and plunger release sleeve of the plunger engagement mechanism shown in FIG. [Figure 11B] FIG. 11B is a cross-sectional view of the actuator and plunger release sleeve shown in FIG. [Figure 12] FIG. 16 is a perspective view of a plunger engagement post of the plunger engagement mechanism shown in FIGS. 9 and 13A-13J. [Figure 13A] 10 is a cross-sectional perspective view of the operation of the piston and plunger engagement mechanism of FIG. [Figure 13B] 10 is a cross-sectional perspective view of the operation of the piston and plunger engagement mechanism of FIG. [Figure 13C] 10 is a cross-sectional perspective view of the operation of the piston and plunger engagement mechanism of FIG. [Figure 13D] 10 is a cross-sectional perspective view of the operation of the piston and plunger engagement mechanism of FIG. [Figure 13E] 10 is a cross-sectional perspective view of the operation of the piston and plunger engagement mechanism of FIG. [Figure 13F] 10 is a cross-sectional perspective view of the operation of the piston and plunger engagement mechanism of FIG. [Figure 13G] 10 is a cross-sectional perspective view of the operation of the piston and plunger engagement mechanism of FIG. [Figure 13H] 10 is a cross-sectional perspective view of the operation of the piston and plunger engagement mechanism of FIG. [Figure 13I] 10 is a cross-sectional perspective view of the operation of the piston and plunger engagement mechanism of FIG. [Figure 13J] 10 is a cross-sectional perspective view of the operation of the piston and plunger engagement mechanism of FIG. [Figure 14A] 11A-11C are cross-sectional views of the operation of a piston of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 14B]11A-11C are cross-sectional views of the operation of a piston of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 14C] 11A-11C are cross-sectional views of the operation of a piston of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 15] FIG. 15 is a perspective view of a plunger engagement post of the plunger engagement mechanism shown in FIGS. 14A-14C. [Figure 16] FIG. 15 is a perspective view of a plunger release sleeve of the plunger engagement mechanism shown in FIGS. 14A-14C. [Figure 17A] FIG. 15 is a perspective view of a plunger engagement sleeve of the plunger engagement mechanism shown in FIGS. 14A to 14C. [Figure 17B] 14A to 14C. FIG. 14B is a cross-sectional perspective view of a plunger engagement sleeve of the plunger engagement mechanism shown in FIGS. [Figure 18A] 13A-13C are cross-sectional perspective views of the operation of a piston of a plunger engagement mechanism according to another embodiment of the present disclosure; [Figure 18B] FIG. 18B is a perspective view of a plunger engagement post of the plunger engagement mechanism shown in FIG. 18A. [Figure 19] 13 is a perspective view of a piston of a fluid injector system having a plunger engagement mechanism according to another embodiment of the present disclosure. FIG. [Figure 20] FIG. 20 is an exploded perspective view of the plunger engagement mechanism of FIG. 19. [Figure 21A] 20 is a cross-sectional view of the operation of the plunger engagement mechanism of FIG. 19. [Figure 21B] 20 is a cross-sectional view of the operation of the plunger engagement mechanism of FIG. 19. [Figure 22A] 11A-11C are cross-sectional views of the operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 22B] 11A-11C are cross-sectional views of the operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 22C] 11A-11C are cross-sectional views of the operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 22D] 11A-11C are cross-sectional views of the operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 22E]11A-11C are cross-sectional views of the operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 23A] 11A-11C are cross-sectional views of a piston in operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 23B] 11A-11C are cross-sectional views of a piston in operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 23C] 11A-11C are cross-sectional views of a piston in operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 23D] 11A-11C are cross-sectional views of a piston in operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 23E] 11A-11C are cross-sectional views of a piston in operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 23F] 11A-11C are cross-sectional views of a piston in operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 23G] 11A-11C are cross-sectional views of a piston in operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 24A] FIG. 13 is a perspective view of a piston having a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 24B] FIG. 24B is an exploded view of the plunger engagement mechanism of FIG. 24A. [Figure 24C] FIG. 24B is a cross-sectional view of the piston and plunger engagement mechanism of FIG. 24A. [Figure 25A] 11A-11C are cross-sectional views of a piston in operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 25B] 11A-11C are cross-sectional views of a piston in operation of a plunger engagement mechanism according to another embodiment of the present disclosure. [Figure 26] 13 is a cross-sectional perspective view of a piston of a fluid injector system having a plunger engagement mechanism according to another embodiment of the present disclosure. FIG. [Figure 27A] FIG. 27 is a perspective view of the plunger engagement sleeve of the plunger engagement mechanism of FIG. 26; [Figure 27B] 27 is a cross-sectional perspective view of the plunger engagement sleeve of the plunger engagement mechanism of FIG. 26. FIG. [Figure 28]FIG. 27 is a perspective view of the plunger release sleeve of the plunger engagement mechanism of FIG. 26; [Figure 29] 27 is a cross-sectional perspective view of a plunger engagement post of the plunger engagement mechanism shown in FIG. 26. FIG. [Figure 30A] 27 is a cross-sectional perspective view of the engagement operation of the piston and plunger engagement mechanism of FIG. 26, with the plunger engagement mechanism shown at one stage during engagement of the plunger. [Figure 30B] 27 is a cross-sectional perspective view of the engagement operation of the piston and plunger engagement mechanism of FIG. 26, with the plunger engagement mechanism shown at one stage during engagement of the plunger. [Figure 30C] 27 is a cross-sectional perspective view of the engagement operation of the piston and plunger engagement mechanism of FIG. 26, with the plunger engagement mechanism shown at one stage during engagement of the plunger. [Figure 30D] 27 is a cross-sectional perspective view of the engagement operation of the piston and plunger engagement mechanism of FIG. 26, with the plunger engagement mechanism shown at one stage during engagement of the plunger. [Figure 31A] 27 is a cross-sectional perspective view of a disengagement operation of the piston and plunger engagement mechanism of FIG. 26, with the plunger engagement mechanism shown at one stage during disengagement of the plunger. [Figure 31B] 27 is a cross-sectional perspective view of a disengagement operation of the piston and plunger engagement mechanism of FIG. 26, with the plunger engagement mechanism shown at one stage during disengagement of the plunger. [Figure 31C] 27 is a cross-sectional perspective view of a disengagement operation of the piston and plunger engagement mechanism of FIG. 26, with the plunger engagement mechanism shown at one stage during disengagement of the plunger. [Figure 31D] 27 is a cross-sectional perspective view of a disengagement operation of the piston and plunger engagement mechanism of FIG. 26, with the plunger engagement mechanism shown at one stage during disengagement of the plunger. [Diagram 32] FIG. 13 is a top view of a system including a fluid infuser and a pressure jacket according to another embodiment of the present disclosure. [Diagram 33] FIG. 33 is an exploded top view of the system of FIG. 32. [Diagram 34]FIG. 13 is a perspective view of a pair of pressure jackets according to another embodiment of the present disclosure. [Figure 35A] FIG. 13 is a perspective view of a syringe cap according to another embodiment of the present disclosure. [Figure 35B] FIG. 13 is a perspective view of a syringe assembly according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0136] For purposes of the following description, the terms "top," "bottom," "right," "left," "vertical," "horizontal," "top," "bottom," "transverse," "longitudinal," and derivatives thereof shall refer to the present disclosure as depicted in the drawings. Spatial or directional terms such as "left," "right," "inner," "outer," "upper," and "lower" should not be considered limiting as the embodiments described herein may assume various alternative orientations.

[0137] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. All numbers used in the specification and claims should be understood as being modified in all instances by the term "about." The terms "approximately," "about," and "substantially" refer to a range of plus or minus ten percent of the stated value.

[0138] Unless otherwise indicated, all ranges or ratios disclosed herein should be understood to include the starting and ending values ​​and any and all subranges or subratios subsumed therein. For example, a range or ratio described as "1 to 10" should be considered to include any and all subranges or subratios between (and including) the minimum value of 1 and the maximum value of 10, i.e., all subranges or subratios beginning with a minimum value of 1 or greater and ending with a maximum value of 10 or less. The ranges and / or ratios disclosed herein represent average values ​​across the specified ranges and / or ratios.

[0139] As used herein, the term "at least one" is synonymous with "one or more." 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 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" is synonymous with "two or more." 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, one or more of D and one or more of F, one or more of E and one or more of F, or one or more of all of D, E, and F.

[0140] Terms such as "first," "second," and the like are not intended to refer to a particular order or chronology, but rather to different conditions, characteristics, or elements. All documents mentioned herein are "incorporated by reference" in their entirety. The term "at least" is synonymous with "more than or equal to." The term "not more than" is synonymous with "less than or equal to."

[0141] It should be understood that the present disclosure may contemplate alternative variations and step sequences unless expressly specified otherwise. It should also be understood that the specific devices and processes illustrated in the accompanying drawings and described in the following specification are merely exemplary embodiments of the present disclosure. Hence, specific dimensions and other physical characteristics relating to the examples disclosed herein are not to be considered as limiting.

[0142] As used herein, the terms "parallel" or "substantially parallel" refer to a relative angle involving a reference line between two objects, such as elongated objects (when extended to a theoretical intersection point), that is 0° to 5°, or 0° to 3°, or 0° to 2°, or 0° to 1°, or 0° to 0.5°, or 0° to 0.25°, or 0° to 0.1°, inclusive of the recited values.

[0143] As used herein, the terms "vertical" or "substantially vertical" mean that the relative angle between two objects at their actual or theoretical 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°, inclusive of the recited values.

[0144] When used in relation to a component of a fluid delivery system, such as a fluid reservoir, a syringe, a pressure jacket, or a fluid line, the term "distal" refers to the portion of said component closest to the patient. When used in relation to a component of an injector system, such as a fluid reservoir, a syringe, a pressure jacket, or a fluid line, the term "proximal" refers to the portion of said component closest to the injector of the injector system (i.e., the portion of said component furthest from the patient). When used in relation to a component of a fluid delivery system, such as a fluid line, the term "upstream" refers to a direction away from the patient toward the injector of the injector system. For example, if a first component is referred to as being "upstream" of a second component, the first component is located closer to the injector than the second component. When used in relation to a component of a fluid delivery system, such as a fluid line, the term "downstream" refers to a direction away from the injector of the fluid delivery system toward the patient. For example, if a first component is referred to as being "downstream" of a second component, the first component is located closer to the patient than the second component.

[0145] When used in connection with movement of a component of a fluid delivery system, such as one or more components of a plunger engagement mechanism associated with a piston, the terms "automatic" or "automatically" refer to movement of the one or more components without manual assistance.

[0146] Although the systems and devices described herein refer 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 can also incorporate the various embodiments described herein for securing a syringe plunger to a piston of a fluid injector.

[0147] With reference to the drawings, in which like reference numerals refer to like parts throughout the several views, the present disclosure 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 decoupled from the piston. In various embodiments, such a piston can be manually, mechanically, hydraulically, or electrically actuated. Furthermore, the present disclosure provides a quick and easy solution for engaging and / or decoupling a syringe plunger from a piston without a specific rotational orientation or alignment of the plunger relative to the piston. For example, the piston may be advanced forward until it engages with the plunger, regardless of the orientation of the plunger about its longitudinal axis relative to the longitudinal axis of the piston, as described in more detail herein. Additionally, when the piston may be attached to the plunger, simple rotation of the plunger by rotation of the syringe, for example, about its longitudinal axis relative to the piston, may cause separation of the two elements. In another embodiment, engagement and disengagement of the piston from the plunger may be performed by the fluid injector controller, either automatically as part of a programmed injection protocol, such as during initiation and completion of a fluid injection protocol, or initiated by a user, e.g., by user input to the fluid injector controller. In a further embodiment or aspect, the present disclosure is also directed generally to pressure jackets and caps for pressure jackets, where the same connection interface for connecting a syringe plunger to a piston of a fluid injector may be used to connect the pressure jacket to a fluid injector and / or the cap of the pressure jacket to the pressure jacket itself.

[0148] With reference to FIG. 1, a non-limiting example of a fluid injector system 10 (hereinafter referred to as "injector 10"), such as an automatic or powered fluid injector, is adapted to interact with and actuate at least one syringe 12 and corresponding plunger 26, each of which may be independently filled with a medical fluid F, such as contrast medium, saline, or any desired medical fluid. The injector 10 may be used during a medical procedure to inject a medical fluid into a patient's body by driving the plunger 26 of at least one syringe 12 with at least one drive member, such as at least one piston 13 (shown in FIG. 2). The injector 10 may be a multi-syringe injector, in which several syringes 12 may be oriented side-by-side or in other relationships and may include plungers 26 that are separately actuated by respective pistons 13 associated with the injector 10. In an embodiment in which two syringes are arranged side-by-side and filled with two different medical fluids, the injector 10 may deliver fluid from one or both of the syringes 12.

[0149] Injector 10 may be enclosed within a housing 14 formed from a suitable material of construction, such as plastic or metal. Housing 14 may be of a variety of shapes and sizes depending on the desired application. Injector 10 includes at least one syringe port 16 for connecting at least one syringe 12 to a respective piston 13 (FIG. 2).

[0150] At least one fluid pathway set 17 may be fluidly connected to at least one syringe 12 for delivery of medical fluid F from the at least one syringe 12 to a catheter, needle, or other fluid delivery connection (not shown) inserted into a patient at a vascular access site. Fluid flow from the at least one syringe 12 may be regulated by a controller 200 (FIG. 2). The controller 200 may operate various pistons, piston mechanical components (such as components for engaging and disengaging the piston with a plunger), valves, and / or flow regulating structures to regulate delivery of medical fluids, such as saline and contrast, to a patient based on user-selected injection parameters. One aspect of a suitable front-loading fluid injector that may be modified for use with the above-described system including at least one syringe and at least one piston for engaging and releasably holding the plunger of the syringe engaged with the fluid injector described herein with reference to Figures 1-2 is disclosed in U.S. Patent No. 5,399,623, and another aspect of a related multi-fluid delivery system that may be modified for use with the present system is found in U.S. Patent No. 5,399,623, U.S. Patent No. 5,399,623, International Application US2012 / 037491, and U.S. Patent No. 5,399,623, the disclosures of each of which are incorporated herein by reference. Other embodiments may include new fluid injector systems designed to include various embodiments of the connection interface between the piston 13 of the injector 10 and the plunger 26 of the syringe 12 described herein.

[0151] 3, an exemplary embodiment of a dual syringe angiography injector system 100 (hereinafter referred to as "injector 100") is shown. Injector 100 is configured to inject two medical fluids through a first fluid path 17A for a medical fluid, such as an imaging contrast medium for an angiography injection procedure, and a second fluid path 17B for a flushing fluid, such as saline or lactated Ringer's solution. Injector 100 can include an injector housing 14 having two syringe ports 16 configured to engage two syringes 12.

[0152] The injector housing 14 may further include at least one user interface 11 through which an operator can view and control the status of the injection process. The user interface 11 may be in operative communication with a controller (similar to controller 200 described herein, FIG. 2) that sends and receives commands to and from the user interface 11.

[0153] The injector 100 may further include at least one upstream air detector 240 for detecting one or more air bubbles in an air detection tube region 250 of the first and second fluid paths 17A, 17B. The air detection tube region 250 may be associated with a proximal portion of the first and second fluid paths 17A, 17B, for example. The at least one air detector 240 may be an ultrasonic sensor configured to detect one or more air bubbles in the fluid paths. ,light It may include sensors, etc.

[0154] 3, injector 100 may further include bulk fluid containers 19A and 19B for filling and refilling each syringe 12 with imaging contrast medium and flushing fluid, respectively. Bulk fluid containers 19A and 19B may be in selective fluid communication with syringe 12 via respective bulk fluid paths 21A and 21B and bulk fluid valves 23A and 23B.

[0155] Further details and examples of suitable non-limiting power injector systems, including syringes, controllers, and air detectors, are described in U.S. Patent Nos. 5,233,339, 5,396, 5,431, 5,523, 5,611, 5,721, 5,893, 6,946, 6,103, 6,143, 6,151, 6,166, 6,271, 6,281, 6,292, 7,366, 7,471, 7,521, 7,282, 7,376, 7,297, 8,296, 9,297, and 5,377, 7,282, the disclosures of which are incorporated herein by reference in their entireties. Although injector 100 is described herein in the context of a dual syringe angiography (CV) injector, it should be understood that injector 100 may be adapted for single and multiple syringe configurations for any injection procedure (e.g., CT, PET, MRI, ultrasound, etc.).

[0156] Injector 100 may include pistons, similar to piston 13 described herein in FIG. 2, respectively associated with each of the syringes 12. Each piston is configured to drive a respective plunger within the barrel of the respective syringe 12. Due to the high pressures associated with CV angiography procedures, syringes 12 may be inserted into a pressure jacket 15 to control radial expansion of the syringes. A controller is operatively associated with the pistons to reciprocate the plungers within syringes 12, thereby performing the injection procedure.

[0157] The controller may be programmed or configured to execute a fill operation in which a piston associated with each syringe 12 is retracted toward the proximal end of the syringe 12 to draw injection fluid (e.g., imaging contrast medium and flushing fluid) from the bulk fluid containers 19A, 19B into the syringe 12. During such a fill operation, the controller may be programmed or configured to selectively actuate bulk fluid valves 23A and 23B to establish fluid communication between the respective syringes 12 and the bulk fluid containers 19A, 19B via bulk fluid paths 21A and 21B to control the filling of the syringes 12 with the appropriate injection fluid. Upon completion of the filing operation, and optionally a priming operation to remove air from the syringe 12 (e.g., by priming such air into the bulk fluid containers 19A, 19B or via the priming tube), the controller may be programmed or configured to selectively actuate the bulk fluid valves 23A and 23B to block fluid communication between the respective syringes 12 and the bulk fluid containers 19A, 19B via the bulk fluid paths 17A and 17B.

[0158] After the filling and priming operations, the controller may be programmed or configured to execute a delivery operation in which a piston associated with one or both of the syringes 12 is moved toward a distal end of the syringe 12 to inject the injection fluid into the first and second fluid paths 17A, 17B. The controller may be programmed or configured to selectively actuate the fluid valves 23A and 23B to establish fluid communication between the syringe 12 and the patient via the fluid paths 17A, 17B. According to various embodiments, the first and second fluid paths 17A and 17B may meet at a fluid mixing connector that provides turbulent mixing between the first and second fluids, such as the fluid mixing connectors described in International Application Publication No. US2021 / 019507 and International Application Publication No. US2014 / 026324, the disclosures of which are incorporated herein by reference.

[0159] Referring now to FIG. 4, a schematic diagram of exemplary components of one embodiment of a controller 200 for implementing and executing the systems and methods described herein, according to an embodiment of the present disclosure, is shown. In some embodiments, the controller 200 may include additional, fewer, different, or differently arranged components relative to those shown in FIG. 4. The controller 200 may include a bus 202, at least one processor 204, a memory 206, a storage component 208, an input component 210 (such as a GUI, keyboard, or other user interface 11, shown in FIG. 3), 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 components that allow 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, the 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.). The memory 206 may include random access memory (RAM), read only memory (ROM), and / or other types of dynamic or static storage devices (e.g., flash memory, magnetic memory, optical memory, etc.) that store information and / or instructions for use by the at least one processor 204.

[0160] The storage component 208 can store information and / or software related to the operation and use of the controller 200. For example, the storage component 208 can include a hard disk and / or another type of computer-readable medium. The input component 210 can include components that allow the 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.). Additionally or alternatively, the input component 210 can include sensors for sensing information (e.g., a global positioning system (GPS) component, an accelerometer, a gyroscope, an actuator, etc.). The output component 212 can include components that provide output information from the controller 200 (e.g., a GUI, a display, a speaker, one or more light emitting diodes (LEDs), etc.). The communication interface 214 can include transceiver-like components (e.g., a transceiver, a separate receiver and transmitter, etc.) that allow the controller 200 to communicate with other devices, such as via a wired connection, a wireless connection, or a combination of wired and wireless connections. The communications interface 214 may allow the controller 200 to receive information from another apparatus and / or provide information to another device. The input component 210, the output component 212, and / or the communications interface 214 may correspond to or be components of the user interface 11 (see FIG. 3).

[0161] The controller 200 can perform the methods described herein based on at least one processor 204 executing software instructions stored by a computer-readable medium such as memory 206 and / or storage component 208. The computer-readable medium can include any non-transitory memory device. The memory device includes a memory space located in a single physical storage device or a memory space spread across multiple physical storage devices. The software instructions may be loaded into the memory 206 and / or storage component 208 from another computer-readable medium or from another device via the communication interface 214. When executed, the software instructions stored in the memory 206 and / or storage component 208 can cause the processor 204 to perform one or more processes described herein. Additionally or alternatively, hardwired circuitry may be used in place of or in combination with software instructions to perform one or more processes described herein.

[0162] Having described the overall structure and function of the injector 10, 100, a non-limiting embodiment of a syringe 300 configured for use with the injector 10 of FIGS. 1-2 or the injector 100 of FIG. 3 will now be described in more detail with reference to FIGS. 5A-5B. The syringe 300 generally has a cylindrical syringe barrel 318 formed from glass, metal, or a suitable medical grade plastic. The barrel 318 has a proximal end 320 and a distal end 324 with a sidewall 319 (shown in FIG. 5B) extending therebetween along the length of a syringe longitudinal axis 315 that extends through the center of the barrel 318. The barrel 318 may be made from a transparent or translucent material. A nozzle 322 extends from the distal end 324 of the barrel 318. 5B, the barrel 318 has an outer surface 321 and an inner surface 323 that defines an interior volume 325 configured to receive a fluid therein. The proximal end 320 of the barrel 318 may be sealed with a plunger 326 that is slidable through the barrel 318. The plunger 326 forms a fluid-tight seal against the inner surface 323 of the sidewall 319 of the barrel 318 as the plunger 326 advances through the barrel 318. The plunger 326 is configured to releasably engage a piston of the fluid injector 10, 100 according to various engagement mechanisms described herein.

[0163] The drip flange 335 extends radially outward from the outer surface 321 of the syringe barrel 318 and can prevent fluid dripping from the nozzle 322 from entering the syringe port of the injector. In some embodiments, the drip flange 335 defines a stop surface that delimits the insertion section 330 of the syringe 300.

[0164] 5A, in some embodiments, the proximal end 320 of the syringe 300 is sized and adapted to be removably inserted into a syringe port of the injector 10, 100 (shown in FIGS. 1 and 3) or into a pressure jacket (not shown) engaged with a fluid injector. The proximal end 320 of the syringe 300 can define an insertion section 330 that is removably inserted into a syringe port of the injector 10 shown in FIG. 1 or the injector 100 shown in FIG. 3, while the remainder of the syringe 300 remains outside the syringe port. In another embodiment, the syringe 300 may be inserted into a hole in the pressure jacket and releasably retained within one or more retention features, for example, as described in International Application US2020 / 049885, the disclosure of which is incorporated herein by reference. In certain embodiments, the proximal end 320 of the syringe 300 includes one or more syringe retaining members 331 adapted to form a locking engagement with a corresponding locking mechanism in the syringe port of the injector 10, 100 to releasably retain the syringe 300 within the syringe port. Suitable non-limiting configurations for the retaining members for releasably locking the syringe 300 to the injector 10, 100 are described in U.S. Patent Nos. 5,399,623 and 5,433,362, the disclosures of which are incorporated herein by reference in their entireties. The syringe 300 has been omitted from many of the views of the corresponding plunger engagement mechanisms of this disclosure for clarity.

[0165] 6-8C, a plunger 326 is shown according to one embodiment of the present disclosure. 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 from glass, metal, or a suitable medical grade plastic.

[0166] The plunger body 332 has an internal cavity 340 ( FIG. 7 ) having a conical portion 342 at a distal end 338 of the plunger body 332 and a cylindrical portion 344 at a proximal end 336 of the plunger body 332. The conical portion 342 may be integrally formed with the cylindrical portion 344. In some embodiments, the conical portion 342 may be affixed or otherwise secured to the cylindrical portion 344 of the plunger body 332 using, for example, a friction fit and / or adhesive, welding, or by molding. The conical portion 342 may have a frustum-shaped end 346 having a molded boss 348 configured to engage a sensing member, as described herein. In some embodiments, the distal end 338 of the plunger body 332 may be open or enclosed. In some embodiments, the cylindrical portion 344 may have a ledge 345 projecting radially outwardly relative to the longitudinal axis 334. In this manner, ledge 345 divides cylindrical portion 344 into a first portion 347a having a first inner diameter and a second portion 347b having a second inner diameter that is larger than the first inner diameter.

[0167] With reference to FIG. 7 , the plunger 326 can have one or more release tabs 380 protruding from an inner surface 352 of the internal cavity 340 of the plunger body 332. In some embodiments, the one or more release tabs 380 may protrude radially inward from the inner surface 352 of at least a portion of the cylindrically shaped portion 344 of the plunger body 332, such as the first portion 347a. The one or more release tabs 380 may be configured to interact with at least a portion of a plunger engagement feature on the piston to release the plunger 326 from the piston upon rotation of the plunger 326 about its longitudinal axis 334, such as by rotation of the syringe 300. In some embodiments, the multiple release tabs 380 may be radially separated relative to the plunger longitudinal axis 334 along the periphery of the inner surface 352 of the internal cavity 340. In such embodiments, the release tabs 380 are separated from one another by portions of the inner surface 352 of the internal cavity 340. In embodiments where three or more release tabs 380 are provided, the release tabs 380 may be evenly spaced from one another. In some embodiments, the release tabs 380 may have a non-uniform angular spread and / or non-uniform angular spacing between the retention ribs 350 about the inner surface 352 of the internal cavity 340. The proximal end 382 of each release tab 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 feature, as in accordance with certain embodiments described herein.

[0168] 6, the plunger 326 can have a plunger cover 357 having a resilient seal 358 covering at least a portion of an outer surface 360 ​​of the plunger body 332. The seal 358 can be a flexible seal that engages with an inner surface 323 (shown in FIG. 5B) of the syringe barrel 318 such that the seal 358 fluid-tightly seals the interior volume 325 of the syringe barrel 318. The seal 358 can be provided separately from the plunger body 332 or can be integrally formed, such as co-molded, with the plunger body 332. In some embodiments, the outer surface 360 ​​of the plunger body 332 can have a circumferential groove 362. At least a portion of the seal 358 can be retained within the circumferential groove 362. The outer surface 364 of the seal 358 can have one or more lips, protrusions, or other sealing elements 366 that slidingly engage the inner surface of the syringe barrel 318. In some embodiments, at least the sealing element 366 of the seal 358 may be made from an elastomeric material that resiliently engages the inner surface 323 of the syringe barrel 18. At least one extension 356 on the plunger body 332 can prevent the seal 358 from moving out of axial alignment with the syringe 300 as the plunger 326 is moved through the syringe barrel 318.

[0169] 7, the plunger 326 can have at least one resiliently deflectable retaining member 368 (hereinafter, "retaining member 368") protruding proximally from the plunger body 332. In some embodiments, the at least one retaining member 368 can protrude proximally from the inner surface 352 of the internal cavity 340 of the plunger body 332. The at least one retaining member 368 has a first distal end 370 connected to the plunger body 332 and a second proximal end 372 radially deflectable relative to the first end 370 in a direction toward the longitudinal axis 334 and / or away from the bottom. As described herein, the second end 372 can be radially deflectable relative to the first end 370 when the at least one retaining member 368 engages at least a portion of a plunger engagement feature on a piston of the injector 10, 100 (FIGS. 1 and 3). That is, when a portion of the plunger engagement mechanism is moved distally to contact the retaining member 368, the retaining member 368 is biased radially by the portion of the plunger engagement mechanism. Similarly, during a disengagement operation of the piston from the plunger, when a portion of the plunger engagement mechanism is moved proximally to contact the retaining member 368, the retaining member 368 is biased radially by the portion of the plunger engagement mechanism. The first end 370 and the second end 372 may be spaced apart in a direction that extends substantially along the direction of the plunger longitudinal axis 334 of the plunger 326. At least one retaining member 368 may be linearly or curvilinearly continuous between the first end 370 and the second end 372. In some embodiments, the one or more retaining members 368 may extend in a direction parallel to the direction of the plunger longitudinal axis 334. In another embodiment, the one or more retaining members 368 may extend in a direction that is oblique to the direction of the plunger longitudinal axis 334. For example, one or more retention 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 .

[0170] In some embodiments, the plurality of retaining members 368 are radially spaced apart from the plunger longitudinal axis 334 along the periphery of the inner surface 352 of the internal cavity 340. In such embodiments, the retaining members 368 are separated from one another by portions of the inner surface 352 of the internal cavity 340. In embodiments in which three or more retaining members 368 are provided, the retaining members 368 may be evenly spaced apart from one another. For example, in one exemplary, non-limiting embodiment having six retaining members 368 with equal angular separation, as shown in FIGS. 7-8C, each retaining member 368 is 60 degrees apart from adjacent retaining members 368 on either side. In some embodiments, the retaining members 368 may have a non-uniform angular spread and / or a non-uniform angular spacing between the retaining members 368 around the inner surface 352 of the internal cavity 340. The radial spacing of at least one retaining member 368 relative to the plunger longitudinal axis 334 is selected to correspond to the periphery of the piston, as described herein.

[0171] The second end 372 of the retaining member 368 has at least one catch 374. The at least one catch 374 protrudes radially from the retaining member 368. The at least one catch 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 by the at least one catch 374. In some embodiments, the at least one catch 374 may protrude 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 radially outward due to contact between the catch 374 and at least a portion of the piston-like plunger engagement mechanism, as described herein. In some embodiments, the at least one catch 374 may protrude radially outward away from the plunger longitudinal axis 334 of the plunger body 332. As such, the at least one retaining member 368 is configured to be biased radially inward due to contact between the catch 374 and at least a portion of a plunger engagement feature on the piston, as described herein, and the at least one retaining member 368 is configured to return toward its undeflected state by moving radially inward.

[0172] The at least one catch 374 may be integrally formed with the second end 372 of the at least one retaining member 368 or may be affixed or otherwise secured to the second end 372 of the at least one retaining member 368, for example, using a friction fit and / or adhesive, welding, or by co-molding. In another embodiment, the at least one catch 374 may be formed on the second end 372 of the at least one retaining member 368 by etching, laser cutting, or machining. As described herein, the at least one catch 374 is shaped to be received within a catch receiving space or groove of a plunger engagement mechanism provided on the piston of the injector 10, 100 to lock the at least one retaining member 368 relative to the piston when the plunger engagement mechanism is in a locked state or position according to an embodiment of the mechanism described herein. As shown in FIGS. 7-8C, the catch 374 may have a distal surface 377 with rounded edges. In some embodiments, the catch 374 can have a proximal surface 379 with rounded edges. The shape of the distal surface 377 and the proximal surface 379 can be such that the catch 374 cannot, by itself, form a locking engagement with a corresponding locking feature on the plunger engagement mechanism of the piston. Instead, the catch 374 must act in conjunction with actuation of the plunger engagement mechanism to form a locking engagement with the piston.

[0173] 8A-8C, plungers 326 according to various embodiments of the present disclosure are shown. The components of plunger 326 shown in Figures 8A-8C are substantially similar or identical to the components of plunger 326 described herein with reference to Figures 6-7. Accordingly, reference numbers in Figures 8A-8C are used to indicate the same components with corresponding reference numbers in Figures 6-7, and only the relative differences between the embodiments of plunger 326 are described herein.

[0174] 8A-8C, the plunger 326 can have one or more release tabs 380 protruding from an inner surface 352 of at least a portion of the cylindrical portion 344 of the plunger body 332, such as the second portion 347b. The one or more release tabs 380 may protrude axially from the ledge 345 and radially inward from the inner surface 352 of the second portion 347b of the cylindrical portion 344, or may protrude radially inward from the inner surface 352 of the second portion 347b along the entire width of the ledge 345 (FIG. 8A) or along a portion of the width of the ledge 345 (FIGS. 8B and 8C). As described herein, the one or more release tabs 380 are configured to interact with at least a portion of a plunger engagement feature on the piston to cause release of the plunger 326 from the piston upon rotation of the plunger 326 about its longitudinal axis 334, such as by rotation of the syringe 300.

[0175] The embodiment of the plunger 326 in FIG. 8C has at least one retaining member 368 having a catch 374 that projects radially outwardly, away from the plunger longitudinal axis 334. As such, the at least one retaining member 368 shown in FIG. 8C is configured to be biased radially inwardly due to contact between the catch 374 and at least a portion of a plunger engagement feature on the piston, as described herein. The at least one retaining member 368 shown in FIG. 8C is configured to return toward its undeflected state by moving radially outwardly.

[0176] With reference to FIG. 9, an embodiment of the piston 400 is shown separate from the injector. In another embodiment, the piston 400 may be configured for use with a fluid injector as 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 FIG. 2), a hydraulic system, a pneumatic system, or any combination thereof. The controller 200 (FIG. 2) may be configured to control the operation of the drive mechanism, and thus the reciprocating movement of the piston 400. In certain embodiments, the controller 200 may be configured to control the engagement and / or disengagement of the piston 400 with a plunger.

[0177] 9, the piston 400 has a body 404 and a piston head 406 at a distal end of the body 404. The piston head 406 is configured to be removably connected to a plunger of a syringe, such as the plunger 326 shown in FIG. 8C. The piston head 406 extends radially outward beyond a radial edge of the body 404. The piston 400 is constructed from a relatively rigid material, such as a metal, plastic, or a combination thereof, that is resistant to deformation. The piston head 406 has a substantially cylindrical structure with a distal end configured to be received inside at least a portion of the internal cavity 340 (FIG. 8C) of the plunger 326. In some embodiments, at least a portion of the piston head 406 may be made from a transparent or translucent material configured to allow the passage of electromagnetic radiation emitted by one or more electromagnetic radiation sources within the piston 400 to illuminate the plunger 326 and / or at least a portion of the syringe 300.

[0178] In some embodiments, a sensing member such as a spring pin (e.g., pin 707, see FIGS. 21A-21B) connected to a sensor may be provided. The sensing member may extend along a longitudinal axis of the piston 400 and may protrude through at least a portion of the piston head 406. The sensing member may be operative to sense contact with a surface, such as surface 348 of the plunger 326, and may control movement of the piston 400 based on the sensed condition. For example, initial contact between the sensing member and surface 348 of the plunger 326 may retract the pin proximally to contact the sensor. The sensor may be connected to a drive mechanism of the piston 400 such that upon actuation of the sensor by the pin, the sensor controls movement of the drive mechanism. For example, the drive mechanism may be stopped or slowed down from a first speed to a second, slower speed.

[0179] 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 (FIGS. 5A-5B). With continued reference to FIG. 9, the plunger engagement mechanism 412 has a plunger engagement sleeve 414 having a central opening 416 and a plunger engagement post 418 reciprocally movable within the central opening 416 of the plunger engagement sleeve 414 along the direction of a longitudinal piston axis 420. The plunger engagement post 418 is reciprocally driven 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 disposed within the plunger engagement sleeve 414 to capture at least one retention member 368 associated with the plunger 326 within 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 permit removal of at least one retention member 368 associated with the plunger 326 from a receiving space 415 between the plunger engagement sleeve 414 and the plunger engagement post 418. FIG. 9 illustrates portions of the plunger engagement mechanism 412 in an engaged position or state and a disengaged position or state. Specifically, the plunger engagement post 418 in FIG. 9 is shown in both its engaged position or state (right side of cross section) and disengaged position or state (left side of cross section). During 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 be linearly and / or rotationally movable relative to the piston 400.

[0180] 10A-10B, the plunger-engaging sleeve 414 has a hollow body 424, at least a portion of an outer surface of the hollow body 424 defining at least a portion of the piston head 406 (shown in FIG. 9). A distal portion or end 426 of the plunger-engaging sleeve 414 is configured to be received in the internal cavity 340 of the plunger 326, while at least a portion of the plunger 326, such as the at least one retaining member 368, is configured to be received within a central opening 416 (see, e.g., FIG. 9). The central opening 416 extends through the hollow body 424 of the plunger-engaging sleeve 414.

[0181] 10B, a portion of the inner surface 428 of the central opening 416 at the distal end of the opening 416 can have a sloped portion 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 the proximal portion or end 432. The sloped portion 430 can be configured to engage the catch 374 and bias the at least one retention member 368 associated with the plunger 326 radially inward during connection of the plunger 326 to the distal portion or end 426 of the plunger engagement sleeve 414. The sloped portion 430 can terminate in a locking rib 434. The at least one catch 374 can flex to abut a proximal face of the locking rib 434 such that the at least one catch 374 can easily flex and pass the locking rib 434 when the piston moves in a proximal direction unless the plunger engagement mechanism 412 moves to the locking engagement configuration. That is, the at least one retaining member 368 and corresponding catch 374 can easily flex and move in and out of the central opening 416 of the plunger engagement sleeve 414 when the piston is in the disengaged configuration. 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 a surface that engages with the at least one catch 374 on the at least one retaining member 368 of the plunger 326 to prevent removal of the plunger 326 from the piston 400 when the plunger 326 is in locking engagement with the plunger engagement feature 412, as described herein. The inner surface 428 of the central opening 416 may be substantially cylindrical proximal to the locking rib 434.

[0182] A proximal portion or end 432 of the hollow body 424 may be integrally formed with the distal portion or end 426 and may have an inner surface 436 having a longitudinal groove 438 configured to receive a guide pin 439 of the plunger engagement post 418 ( FIG. 9 ). The longitudinal groove 438 has a distal stop 440 for determining distal movement of the guide pin 439, thereby delimiting distal movement of the plunger engagement post 418 relative to the plunger engagement sleeve 414. An outer surface 442 of the proximal portion or end 432 of the hollow body 424 may have a toothed portion 444 configured to interact with one or more release tabs 380 on the plunger 326 during removal of the plunger 326 from the plunger engagement mechanism 412.

[0183] 11A-11B, the plunger engagement mechanism 412 further includes a housing 446 configured to receive the actuator 422. As shown in FIG. 11B, the housing 446 may have a cylindrical structure having a connecting member 448 configured to connect with a connector 450 on the actuator 422. In some embodiments, the connecting member 448 on the housing 446 may be a female threaded surface configured to threadably mate with the male threaded connector 450 on the actuator 422. In another embodiment, the connecting member 448 may be an adhesive, a clip, an interference fit, a fastener, or any other connector feature for removably or non-removably connecting the housing 446 to the connector 450 on the actuator 422.

[0184] 11A-11B, the housing 446 has a proximal portion 452 connected to a distal portion 454. In some embodiments, the distal portion 454 may have a smaller outer diameter than the proximal portion 452 such that a ledge 456 is defined at the transition between the proximal portion 452 and the distal portion 454. In some embodiments, the ledge 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.

[0185] 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 with an opening 462 extending therethrough. The opening 462 can have a longitudinal surface 463 that is substantially parallel to a longitudinal axis 464 of the plunger release sleeve 458 and an inclined surface 466 adjacent the longitudinal surface 463 and inclined relative to the longitudinal axis 464 of the plunger release sleeve 458 in a direction from the distal end 468 toward the proximal end 470. As described herein, the longitudinal surface 463 is configured to guide the guide pin 439 of the plunger engagement post 418 ( FIG. 9 ) during movement of the plunger engagement post 418 longitudinally along the longitudinal axis 420 of the piston 400, while the angled 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 lights 472 may be provided on a printed circuit board 474 connected to the distal end 468 of the plunger release sleeve 458. The one or more lights 472 may be configured to illuminate at least a portion of the plunger 326, as described herein.

[0186] 11B, the actuator 422 may be configured to have an engaged state for moving one of the plunger engagement sleeve 414 and the plunger engagement post 418 to an engaged position and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement post to a disengaged position. In some embodiments, the actuator 422 may be automatically moved to the disengaged state, such as during a loss of power to the actuator 422. In some embodiments, the actuator 422 may be in an engaged state only during proximal movement of the piston 400. In some embodiments, the actuator 422 may be a solenoid configured to be primarily in a disengaged state and may be in an engaged state only during connection of the plunger 326 to the piston 400. In another embodiment, the actuator 422 may be a rotary electric motor, a linear electric motor, or a linear actuator. In some embodiments, the actuator 422 is a linear actuator that can be manually back-driven in the event of a loss of power to the injector.

[0187] 9, the plunger engagement sleeve 414 may be rotatable about the longitudinal piston axis 420 relative to the housing 446 and the plunger release sleeve 458 between a first position and a second position. In some embodiments, the plunger engagement sleeve 414 may be rotatable in one of a clockwise and counterclockwise direction or a clockwise and counterclockwise direction. The plunger engagement sleeve 414 may be rotatable from the first position to the second position by rotational movement of the plunger 326 about the longitudinal piston axis 420. For example, the plunger engagement sleeve 414 may be rotatable about the longitudinal axis 420 by interaction of a release tab 390 on the plunger 326 with a toothed portion 444 on the piston engagement sleeve 414. In certain embodiments, rotation of the plunger engagement sleeve 414 may move a guide pin 439 along an inclined surface 466 of the plunger release sleeve 458 to move the plunger engagement post 418 to a disengaged or engaged position. A biasing member 496 may be provided to bias the plunger engaging sleeve 414 toward the first position. In this manner, as the plunger engaging sleeve 414 is rotated from the first position toward the second position, the biasing member 496 builds potential energy that is then used to assist in returning the plunger engaging sleeve 414 toward the first position. In some embodiments, the biasing member 496 may be a torsion spring having one end connected to the plunger engaging sleeve 414 and another end connected to the housing 446 or the plunger release sleeve 458.

[0188] 12, the plunger engagement post 418 is shown separate from the plunger engagement mechanism 412. The plunger engagement post 418 has a shaft 472 having a proximal end 474 and a distal end 476. The distal end 476 of the shaft 472 has a tapered end surface 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 to lock the at least one catch 374 against the locking rib 434 of the plunger engagement sleeve 414 to prevent removal of the plunger 326 from the piston 400. A seal 480 may be provided at the distal end 478 for sealing against the inner surface 428 of the plunger engagement sleeve 414 (shown in FIGS. 10A-10B). The seal 480 may be an O-ring seal.

[0189] 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 disposed substantially perpendicular to a longitudinal axis 482 of the shaft 472. A resilient member 484 surrounds the shaft 472 and has a distal end 486 that abuts a ledge 488 at a distal end 478 of the shaft 472. A proximal end 490 of the resilient member 484 may be configured to contact the actuator 422 or the housing 446. The resilient member 484 may be a compression spring configured to bias the plunger engagement post 418 distally toward the engaged position, as described herein. In another embodiment, the resilient member 484 may be a tension spring configured to bias the plunger engagement post 418 proximally toward the disengaged position.

[0190] Having described the structure of plunger 326 and piston 400 according to one non-limiting embodiment of the present disclosure, a method of engagement and disengagement of plunger 326 from piston 400 will now be described with reference to FIGS. 13A-13J.

[0191] 13A shows the piston 400 with its plunger engagement feature 412 in an engaged position or state and prior to connection with the plunger 326. In some embodiments, the default state of the plunger engagement feature 412 may be the engaged position or state. To connect the plunger 326 to the piston 400, the syringe 300 is first connected to the injector 10, 100 (FIGS. 1 and 3). During connection of the syringe 300 to the injector 10, 100, the piston 400 is retracted into the housing of the injector 10, 100. After connecting the syringe 300 to the injector 10, 100, the piston 400 can be advanced distally toward the plunger 326.

[0192] 13B, the actuator 422 is energized to retract the shaft 472 of the plunger engagement post 418 in a proximal direction, indicated by arrow A, from an engaged position or state to a disengaged position or state. Movement of the shaft 472 in the proximal direction opens up the receiving space 415 between the plunger engagement sleeve 414 and the plunger engagement post 418 to permit insertion or removal of one or more retention members 368 of the plunger 326 into the receiving space 415. Such movement also compresses a resilient elastic member 484 between a ledge 488 at the distal end of the shaft 472 and the actuator 422. Compression of the resilient elastic member 484 builds potential energy therebetween. , solution When released, it can be used to guide the plunger engagement post 418 towards an engaged position or condition.

[0193] In another embodiment, the actuator 422 may be de-energized and the shaft 472 of the plunger engagement post 418 may be retracted from an engaged position or state to a disengaged position or state in a proximal direction indicated by arrow A by the elastic restoring force of the resilient member 484. In such an embodiment, the resilient member 484 may be a tension spring that is stretched from a first state to a second state by actuation of the actuator 422. When the actuator 422 is de-energized, the restoring force of the resilient member 484 urges the plunger engagement post 418 toward the disengaged position or state. In this manner, the plunger engagement post 418 is normally in a disengaged position or state, thereby permitting removal of the plunger 326 from the piston 400 in the event that the actuator 422 is inoperable due to a power loss or the like.

[0194] 13C, the piston 400 can then be moved axially in a distal direction toward the plunger 326 (indicated by arrow B). In some embodiments, the piston 400 may be advanced distally using a drive mechanism 402 (FIG. 2) operated by the controller 200. In another embodiment, the piston can be moved distally manually.

[0195] 13D, the piston 400 is advanced axially in a distal direction such that the 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 catch 374 of the at least one retaining member 368. Because the catch 374 projects radially outward relative to the at least one retaining member 368, the catch 374 is disposed at a greater radial distance from the plunger longitudinal axis 334 than the ramped portion 430 of the central opening 416. In this manner, continued distal movement of the piston 400 biases the at least one retaining member 368 radially inward due to contact between the catch 374 and the ramped portion 430. In an embodiment having multiple retaining members 368, each of the retaining members 368 is biased radially inward.

[0196] During continued axial movement of the piston 400 in the distal direction, the catch 374 is biased over the locking rib 434 of the piston engagement sleeve 414. After the catch 374 is disposed proximally relative to the locking rib 434, distal movement of the piston 400 relative to the plunger 326 is stopped or the plunger 326 moves distally with the piston 400 due to contact between a distal portion or end 426 of the plunger engagement sleeve 414 and the inner surface 352 of the internal cavity 340 of the plunger body 332, and the at least one retaining member 368 can be resiliently biased radially inward such that the catch 374 is disposed proximally of the locking rib 434. In some embodiments, distal movement of the piston 400 relative to the plunger 326 may be stopped upon engagement of a portion of the plunger engagement sleeve 414 with the drive shoulder 327 of the plunger 326. 13D , the at least one retaining member 368 may be deflected radially inward with proximal movement of the piston 400 or distal movement of the plunger 326 (such as by removal of the syringe from the injector) such that the plunger 326 is not in locking engagement with the piston 400. With the plunger 326 connected to the piston 400, one or more release tabs 380 on the plunger 326 are aligned with toothed portions 444 on the outer surface 442 of the plunger engagement sleeve 414. In certain embodiments, the plunger 326 cannot be in an engaged locked position with the piston 400 when the piston 400 is moving distally, and only moves to an engaged locked position upon proximal movement of the piston 400. Such a feature can allow for easy removal of the syringe 300 and plunger 326 after a short distal movement of the piston 400, and can reduce wear on system components and / or motors by only requiring locking engagement when the piston 400 is retracted.

[0197] 13E, the actuator 422 is de-energized to allow the shaft 472 of the 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 another embodiment, the actuator 422 may be energized to move the shaft 472 of the plunger engagement post 418 in a distal direction.

[0198] Distal movement of the shaft 472 closes the receiving space 415 between the plunger engagement sleeve 414 and the plunger engagement post 418 which locks the at least one catch 374 against the locking rib 434 to prevent removal of the one or more retention members 368 of the plunger 326 from the receiving space 415, thus preventing removal of the plunger 326 from the 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 resilient member 484. In another embodiment, the plunger engagement post 418 moves from a disengaged position or state to an engaged position or state due to actuation of the actuator 422 to build potential energy in the resilient member 484. When the plunger engagement post 418 moves to an engaged position or state, at least one retention member 368 of the plunger 326 is captured between the plunger engagement sleeve 414 and the plunger engagement post 418 such that axial movement of the piston 400 results in corresponding axial movement of the plunger 326 within the syringe barrel. The piston 400 and connected plunger 326 can then move back and forth within the barrel 318 of the syringe 300 (FIGS. 5A-5B). In certain embodiments, the piston 400 and connected plunger 326 can move proximally within the barrel 318 and can move distally when the piston 400 is in either an engaged or disengaged position with the plunger 326. In some embodiments, the piston 400 can be advanced 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).

[0199] In certain embodiments involving manual disengagement of the syringe, the syringe 300 may be rotated clockwise or counterclockwise about the syringe longitudinal axis relative to the syringe port to unlock the syringe 300 from the syringe port of the injector and disengage the plunger 326 from the piston 400. Because the plunger 326 is substantially free of rotation due to frictional interaction with the syringe barrel 318, rotation of the syringe 300 also rotates the plunger 326 relative to the piston 400 about the longitudinal piston axis 420. Due to alignment of one or more release tabs 380 on the plunger 326 with the toothed portion 444 on the outer surface 442 of the plunger engagement sleeve 414, rotation of the plunger 326 also rotates the plunger engagement sleeve 414 from a first position to a second position relative to the plunger release sleeve 458 of the plunger engagement mechanism 412. A guide pin 439 on the plunger engagement post 418 is received in a longitudinal groove 438 of the plunger engagement sleeve 414 so that as the plunger engagement sleeve 414 rotates, the plunger engagement post 418 also rotates. Rotation of the plunger engagement post 418 guides the guide pin 439 along the angled surface 466 (see FIG. 13F) of the plunger release sleeve 458, compressing the resilient elastic member 484. Additionally, rotation of the plunger engagement sleeve 414 about the longitudinal piston axis 420 builds potential energy in the biasing member 496.

[0200] In other embodiments, such as when the syringe is housed within a pressure jacket, rotation of the syringe and plunger to disengage the plunger 326 from the piston 400 may not be possible. According to these embodiments, disengagement and engagement of the piston 400 with the plunger 326 may be accomplished electromechanically, for example, using an electric or electrical 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 electrical actuator, such as a solenoid, may be used to move the plunger engagement post 418 between an engaged position and a disengaged position to engage and disengage the plunger 326 relative to the piston 400. When the plunger 326 is in the disengaged position, such as at the end of an injection procedure, the syringe 300 may be removed from the injector, and the injector may be prepared for the next procedure.

[0201] 13G, movement of the guide pin 439 along the inclined surface 466 of the plunger release sleeve 458 moves the plunger engagement post 418 axially in the proximal direction of arrow D from an engaged position or state to a disengaged position or state. In some embodiments, the plunger engagement post 418 can be moved proximally by energizing the actuator 422 to retract the shaft 472 of the plunger engagement post 418. In this manner, the plunger engagement post 418 can be moved manually, such as via rotation of the plunger 326 relative to the piston 400 or via actuation of the actuator 422. Thus, in the event of a power failure, the plunger 326 can be removed from the piston 400. Movement of the plunger engagement post 418 in the proximal direction opens the receiving space 415 between the plunger engagement sleeve 414 and the plunger engagement post 418 to permit removal of one or more retention members 368 of the plunger 326 from the receiving space 415. Additionally, a configuration in which actuation of actuator 422 is only required can reduce wear on system components and / or motors by only requiring locking engagement when piston 400 is moving in the proximal direction.

[0202] When the plunger engagement mechanism 412 is in a disengaged position or state, the syringe 300 can be pulled distally or the piston 400 can be retracted proximally to remove the plunger 326 from the piston 400 and remove the syringe 300 and plunger 326 from the fluid injector. During such relative movement of the piston 400 with respect to the plunger 326 away from one another, the catch 374 is biased above the locking rib 434 of the piston engagement sleeve 414 to permit removal of the one or more retention members 368 from the piston 400. The plunger 326 can then be freely pulled away from the piston 400, as shown in FIG.

[0203] 13I-13J, after the plunger 326 is removed from the piston 400, the plunger engagement sleeve 414 and the plunger engagement post 418 are automatically rotated from the second position to the first position about the longitudinal piston axis 420 (shown in FIG. 9) by the restoring force provided by the biasing member 496. The movement of the plunger engagement sleeve 414 and the plunger engagement post 418 to the first position causes the guide pin 439 to be guided along the inclined surface 466 of the plunger release sleeve 458 toward the distal end of the plunger release sleeve 458 by the restoring force provided by the resilient elastic member 484. This causes the plunger engagement post 418 to move in the distal direction of the arrow E. The position of the plunger engagement feature 412 in FIG. 13J is the same as the position of the plunger engagement feature 412 in FIG. 13A.

[0204] 14A-14C, a piston 500 and plunger engagement mechanism 512 according to another embodiment of the present disclosure are shown. The components of the piston 500 and plunger engagement mechanism 512 shown in FIGS. 14A-14C are substantially similar or identical to the components of the piston 400 and plunger engagement mechanism 412 described herein with reference to FIGS. 9-13J. Accordingly, the reference numbers of FIGS. 14A-14C are used to indicate the same components of the corresponding reference numbers in FIGS. 9-13J, except that the leading digits of the reference numbers used in FIGS. 14A-14C are changed from "4" to "5". For example, the piston described in connection with FIGS. 9-13J is designated with the reference number "400", while the piston in FIGS. 14A-14C is identified with the reference number "500". The above description of the piston 400 and plunger engagement mechanism 412 generally shown in Figures 9-13J is applicable to the piston 500 and plunger engagement mechanism 512 shown in Figures 14A-14C, and therefore only the relative differences between the components shown in those figures will be described below.

[0205] The piston 400 and plunger engagement feature 412 shown in Figures 9-13J are configured to interact with the plunger 326 shown in Figures 6-8B, while the piston 500 and plunger engagement feature 512 shown in Figures 14A-14C are configured to interact with the plunger 326 of Figure 8C. Thus, the at least one retaining member 368 shown in Figures 6-8B is configured to deflect radially outwardly due to contact between the catch 374 and at least a portion of the plunger engagement feature 512 on the piston, as described herein. The at least one retaining member 368 shown in Figures 6-8B is configured to move back toward its undeflected state by moving radially inwardly.

[0206] 14A, the plunger engagement mechanism 512 includes a plunger engagement sleeve 514 having a central opening 516 and a plunger engagement post 518. The plunger engagement post 518 includes a proximal portion 519 rotatably connected to a plunger release sleeve 558 such that the plunger engagement post 518 is rotatable about a longitudinal piston axis 520. With reference to FIG. 15, the proximal portion 519 can include a toothed portion 544 at its distal end. Similar to the toothed portion 444 of the plunger engagement mechanism 412 described herein with reference to FIGS. 9-13J, the toothed portion 544 is configured to interact with a release tab 380 on the plunger 326 (FIGS. 8A, 8B, and 14A). The plunger engagement post 518 further includes a post portion 521 extending distally from the proximal portion 519. In some embodiments, the proximal portion 519 and the post portion 521 may be integrally formed to form a unitary part. One or more openings 523 may be formed in the plunger engagement post 518 through a connecting piece 525 connecting the proximal portion 519 to the post portion 521. The openings 523 may be configured to receive a portion of the plunger engagement sleeve 514 therethrough. An upper surface of the connecting piece 525 defines an engagement surface for contacting at least a portion of the plunger 326, such as the 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 determining distal movement of the guide pin 539, thereby limiting distal movement of the plunger engagement sleeve 514 relative to the plunger engagement post 518.

[0207] The plunger engagement post 518 of FIGS. 14A-14C is rotatable only about the piston longitudinal axis 520. The plunger engagement post 518 may be 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 may be rotatable in one of a clockwise and counterclockwise direction or a clockwise and counterclockwise direction. The plunger engagement post 518 may be rotatable from a first position to a second position by rotational movement of the plunger 326 about the longitudinal piston axis 520. For example, the plunger engagement post 518 may be rotatable about the longitudinal axis 520 by interaction of a release tab 390 on the plunger 326 with a toothed portion 544 on the piston engagement post 518. A biasing member (not shown), similar to biasing member 496 shown in FIG. 9, may be provided to bias the plunger engagement post 518 toward the first position. In this manner, as the plunger engagement post 518 is rotated from the first position toward the second position, the biasing member builds potential energy that is then used to assist in returning the plunger engagement post 518 toward the first position. In some embodiments, the biasing member may be a torsion spring having one end connected to the plunger engagement post 518 and the other end connected to the plunger release sleeve 558.

[0208] 15 , the post portion 521 of the plunger engagement post 518 has a locking groove 527 configured to receive a catch 374 of the at least one flexible retaining member 368 of the plunger 326. The distal end of the post portion 521 may be shaped to deflect the at least one retaining member 368 radially outward upon contact of the catch 374 with an outer surface of the post portion 521. In certain embodiments, the distal end of the post portion 521 may include a ramp to further deflect the at least one retaining member 368 radially outward. In this manner, distal movement of the piston 500 relative to the plunger 326 deflects the at least one retaining member 368 radially outward upon contact between the catch 374 and the outer surface of the post portion 521. In embodiments having multiple retaining members 368, each of the retaining members 368 is biased radially outward.

[0209] 14A, the plunger release sleeve 558 is at least partially received within the hollow body structure of the plunger engagement sleeve 514 and the plunger engagement post 518. With reference to FIG. 16, the plunger release sleeve 558 has a cylindrical sidewall 560 having an opening 562 therethrough. The opening 562 can have a longitudinal surface 563 that is substantially parallel to a longitudinal axis 564 of the plunger release sleeve 558 and an inclined surface 566 adjacent the longitudinal surface 563 and inclined relative to the longitudinal axis 564 of the plunger release sleeve 558 in a direction from the distal end 568 toward the proximal end 570. As described herein, the longitudinal surface 563 is configured to guide the guide pin 539 (FIG. 14A) during movement of the plunger engagement sleeve 514 longitudinally along the longitudinal axis 520 of the piston 500, while the inclined surface 566 is configured to guide the guide pin 539 during rotational movement of the plunger 326 relative to the piston 500 (or vice versa), such as during removal of the plunger 326 from the piston 500.

[0210] 17A-17B, the plunger engagement sleeve 514 is shown separate from the remainder of the plunger engagement mechanism 512. The plunger engagement sleeve 514 has a hollow body 524, at least a portion of which is configured to be received within a proximal portion 519 of the plunger engagement post 518. A distal portion or end 526 of the plunger engagement sleeve 514 is configured to be received through an opening 523 (FIG. 15) of the plunger engagement post 518 and disposed within an internal cavity 340 (FIGS. 14A-14B) of the plunger 326. At least a portion of the plunger 326, including at least one retention member 368, is configured to be received within the central opening 516 and within a receiving space 515 between a post portion 521 of the plunger engagement post 518 and the distal portion or end 526 of the plunger engagement sleeve 514. A portion of the inner surface 528 of the central opening 516 may have a tapered portion 530 such that the inner diameter of the opening 516 narrows in a direction from the distal end 526 of the hollow body toward a proximal portion or end 532. The tapered portion 530 may be configured to bias the at least one retaining member 368 associated with the plunger 326 radially inwardly during connection of the plunger 326 to the piston 500 to create a tight engaging interaction between the catch 374 of the at least one flexible retaining member 368 and the locking groove 527 of the plunger engagement post 518.

[0211] 17A-17B, the hollow body 524 of the plunger engagement sleeve 514 has a throughbore 533 configured to receive a guide pin 539 therethrough. The plunger engagement sleeve 514 is configured to rotate about its longitudinal axis 531 by engagement of the guide pin 539 with an angled surface 566 of the plunger release sleeve 558 upon rotation of the plunger 326 and the plunger engagement post 518.

[0212] Having described the structure of plunger 326 and piston 500 according to one non-limiting embodiment of the present disclosure, a method of engagement and disengagement of plunger 326 from piston 500 will now be described with reference to FIGS. 14A-14C.

[0213] FIG 14B shows the piston 500 with the plunger engagement feature 512 in a disengaged position or state and prior to locking engagement with the plunger 326. In FIG 14B, the piston 500 has been advanced distally towards the plunger 326. In some embodiments, the piston 500 may be advanced distally using the drive mechanism 402 operated by the controller 200 (FIG. 2). In another embodiment, the piston can be moved distally manually.

[0214] 14B , the catch 374 on the at least one retaining member 368 of the plunger 326 is biased radially outward by contact with the outer surface of the post portion 521. After the catch 374 is disposed within the locking groove 527, such as when the upper surface of the connecting piece 525 engages the drive shoulder 327 of the plunger 326, distal movement of the piston 500 relative to the plunger 326 is stopped and the at least one retaining member 368 can be resiliently biased radially inward such that the catch 374 is disposed within the locking groove 527. 14B, due to the flexibility of the material between the first distal end 370 and the second proximal end 372 (see FIG. 7), the at least one retaining member 368 may be deflected radially outward with proximal movement of the piston 500 or distal movement of the plunger 326 (such as by removal of the syringe from the injector) such that the plunger 326 is not in locking engagement with the piston 500. With the plunger 326 in contact with the piston 500 as shown in FIG. 14B, one or more release tabs 380 on the plunger 326 align with the toothed portion 544 on the plunger engagement post 518.

[0215] 14A and 14C, the plunger engaging sleeve 514 moves from a disengaged position or state to an engaged position or state. Such movement of the plunger engaging sleeve 514 may result from de-energizing the actuator and allowing a resilient elastic member, such as the resilient elastic member 484 described herein with reference to FIGS. 9-13J, to axially urge the plunger engaging sleeve 514 in a distal direction. In another embodiment, such movement of the plunger engaging sleeve 514 may result from energizing an actuator to axially urge the plunger engaging sleeve 514 in a distal direction. For example, the actuator may be actuated by a rotary or linear motor to move the actuator distally from a disengaged position to an engaged position. Energizing the actuator in this manner causes the plunger engaging sleeve 514 to move distally building up a resilient restoring force of the resilient elastic member. 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 removal of the one or more retaining members 368 of the plunger 326 from the receiving space 515 and the one or more flexible retaining members 368 and the catch 374 of the locking groove 527. When the plunger engagement sleeve 514 moves to an engaged position or condition, the at least one retaining member 368 of the plunger 326 is captured between the plunger engagement sleeve 514 and the plunger engagement post 518 such that proximal axial movement of the piston 500 results in corresponding proximal axial movement of the plunger 326 within the syringe barrel. The piston 500 and connected plunger 326 can then reciprocate within the barrel 318 of the syringe 300.

[0216] To unlock the syringe 300 from the injector's syringe port and disengage the plunger 326 from the piston 500, the syringe 300 is rotated clockwise or counterclockwise about the syringe longitudinal axis relative to the syringe port. Because the plunger 326 is substantially free from rotation within the syringe barrel 318 due to frictional forces, rotation of the syringe 300 also rotates the plunger 326 relative to the piston 500 about the longitudinal piston axis 520. Due to alignment of one or more release tabs 380 on the plunger 326 with the toothed portion 544 on the plunger engagement post 518, rotation of the plunger 326 also rotates the plunger engagement post 518 from a first position to a second position relative to the plunger release sleeve 558. A guide pin 539 on the plunger engagement sleeve 514 is received within a longitudinal groove 538 of the plunger engagement post 518, so that as the plunger engagement post 518 rotates, the plunger engagement sleeve 514 also rotates. Rotation of the plunger engagement sleeve 514 causes the guide pin 539 to guide along an angled surface 566 of the plunger release sleeve 558 (see FIG. 16 ), moving the plunger engagement sleeve 514 proximally and compressing the resilient member, similar to the operation of the resilient member 484 described herein with reference to FIGS. 9-13J. Additionally, rotation of the plunger engagement post 518 about the longitudinal piston axis 520 can build potential energy in the biasing member, similar to the operation of the biasing member 496 described herein with reference to FIGS. 9-13J.

[0217] Movement of the guide pin 539 along the angled surface 566 of the plunger release sleeve 558 moves the plunger engagement sleeve 514 axially in the proximal direction from an engaged position or state to a disengaged position or state shown in FIG. 14A. In some embodiments, the plunger engagement sleeve 514 can be moved proximally by energizing or de-energizing the actuator to retract the plunger engagement sleeve 514. Proximal movement of the plunger engagement sleeve 514 opens the receiving space 515 between the plunger engagement sleeve 514 and the plunger engagement post 518 to permit removal of the one or more flexible retaining members 368 and the catch 374 of the locking groove 527 and to allow removal of the one or more retaining members 368 of the plunger 326 from the receiving space 515.

[0218] 18A-18B, a piston 600 and plunger engagement mechanism 612 are shown according to another embodiment of the present disclosure. The components of the piston 600 and plunger engagement mechanism 612 shown in FIGS. 18A-18B are substantially similar or identical to the components of the piston 400 and plunger engagement mechanism 412 described herein with reference to FIGS. 9-13J. Accordingly, the reference numbers of FIGS. 18A-18B are used to indicate the same components of the corresponding reference numbers in FIGS. 9-13J, except that the leading digits of the reference numbers used in FIGS. 18A-18B are changed from "4" to "6." For example, the piston described in connection with FIGS. 9-13J is designated with the reference number "400," while the piston in FIGS. 18A-18B is identified with the reference number "600." The above description of the piston 400 and plunger engagement mechanism 412 generally shown in Figures 9-13J is applicable to the piston 600 and plunger engagement mechanism 612 shown in Figures 18A-18B, and therefore only the relative differences between the components shown in those figures will be described below.

[0219] 18A, the plunger engagement mechanism 612 includes a plunger engagement sleeve 614 having a central opening 616 and a plunger engagement post 618 reciprocally movable within the central opening 616 of the plunger engagement sleeve 614 along the direction of a longitudinal piston axis 620. The plunger engagement post 618 is reciprocally driven by an actuator, such as the actuator 422 described herein with reference to FIG. 9. 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 connection of the plunger 326 to the piston. In another embodiment, 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 back-driven in the event of a loss of power to the injector.

[0220] 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 disposed within the plunger engagement sleeve 614 to capture the at least one retention member 368 associated with the plunger 326 within 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 disposed proximally relative to the plunger engagement sleeve 614 to permit removal of the at least one retention member 368 associated with the plunger 326 from the receiving space 615 between the plunger engagement sleeve 614 and the plunger engagement post 618.

[0221] 18A , the plunger-engaging sleeve 614 has a hollow body 624, at least a portion of an outer surface of the hollow body 624 defining at least a portion of the piston head 606. A distal portion or end 626 of the plunger-engaging sleeve 614 is configured to be received in the internal cavity 340 of the plunger 326, while at least a portion of the plunger 326, such as the at least one retention 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-engaging sleeve 614. An inner surface of the central opening 616 can have a tapered portion 630 such that an inner diameter of the opening 616 narrows in a direction from the distal end of the hollow body 624 toward the proximal portion or end. The ramp 630 may be configured to bias at least one retaining member 368 associated with the plunger 326 radially inward during connection of the plunger 326 to the plunger-engaging sleeve 614 by contacting a catch 374 of the one or more flexible retaining members 368 as the piston head 606 moves distally relative to the plunger 326. The ramp 630 may terminate in a locking rib 634. The 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 FIGS. 9-13J. The toothed portion 644 may be configured to interact with one or more release tabs 380 on the plunger 326 during rotation of the plunger 326 relative to the piston 600 (as shown in FIG. 8C).

[0222] 18B, the plunger engagement post 618 is shown separate from the plunger engagement feature 612. The plunger engagement post 618 has a shaft 672 having 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 retention member 368 on the plunger 326 when the plunger engagement post 618 is in an engaged position to prevent removal of the plunger 326 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 FIGS. 9-13J, 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.

[0223] 18B , the plunger engagement post 618 further includes at least one groove 665 recessed into the body of the shaft 672 at the distal end 676. In some embodiments, the at least one groove 665 may be configured to receive the at least one retaining member 368 of the plunger 326 when the plunger engagement post 618 is rotated about the longitudinal axis 667. The at least one groove 665 may be linear or curvilinear and continuous between a ledge 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 the longitudinal axis 667 of the plunger engagement post 618.

[0224] 18B, a plurality of grooves 665 are radially spaced apart from a longitudinal axis 667 along the circumference of a distal end 676 of the shaft 672. In embodiments in which more than two grooves 665 are provided, the grooves 665 are evenly spaced apart from one another and are separated from one another by the 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 one exemplary, non-limiting embodiment having six retaining members 368 with equal angular separation, as shown in FIG. 8C, the corresponding plunger engagement post 618 has six grooves 665 spaced 60 degrees apart from adjacent grooves 665 on either side.

[0225] 18A, the proximal end 674 of the shaft 672 is received in a rotation mechanism 671 slidably mounted within the hollow body 624 of the plunger engagement sleeve 614. In some embodiments, the rotation mechanism 671 may have a first portion 673 slidably mounted within the hollow body 624 and fixed against rotation relative to the plunger engagement sleeve 614, 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 rotation mechanism 671 may be configured to rotate in one direction, such as a clockwise or counterclockwise direction, about the longitudinal axis 620. For example, the rotation mechanism 671 may be a one-way clutch.

[0226] Having described the structure of plunger 326 and piston 600 according to one non-limiting embodiment of the present disclosure, a method of engagement and disengagement of plunger 326 from piston 600 will now be described.

[0227] FIG. 18A shows the piston 600 with its plunger engagement feature 612 in an engaged position or state with the plunger 326. As described herein with reference to FIGS. 13A-13J, the plunger 326 can be coupled to the piston 600 by moving the piston 600 distally to allow insertion of one or more retention members 368 of the plunger 326 into a receiving space 615 between the plunger engagement sleeve 614 and the plunger engagement post 618. In some embodiments, the piston 600 can be advanced distally using a drive mechanism 402 operated by the controller 200 (FIG. 2). In another embodiment, the piston 600 can be moved distally manually.

[0228] The piston 600 advances axially in the distal direction such that at least one retaining member 368 of the plunger 326 is flexibly received within the central opening 616 of the plunger engagement sleeve 614 such that the at least one retaining member 368 is biased radially inward by contact between the catch 374 and the ramp 630. In embodiments having multiple retaining members 368, each of the retaining members 368 is biased radially inward. In some embodiments, there may be guide surfaces on either side of the tapered end face 678 to assist in rotation of the plunger engagement post 618 into the correct orientation for self-alignment with the retaining member 368 of the plunger 326.

[0229] During continued axial movement of the piston 600 in the distal direction, the catch 374 is biased radially inwardly above the locking rib 634 of the piston engagement sleeve 614. After the catch 374 is disposed proximally relative to the locking rib 634, such as when the drive shoulder 327 of the plunger 326 engages a corresponding drive ledge 637 on the piston 600, the distal movement of the piston 600 relative to the plunger 326 is stopped and the at least one retaining member 368 can be resiliently biased radially outwardly such that the catch 374 is disposed proximally of the locking rib 634. In this configuration, the plunger engagement post 618 is still in a disengaged position or state, such as by actuation of an actuator as described herein with reference to FIGS. 9-14C. With the plunger 326 connected to the piston 600, the one or more release tabs 380 on the plunger 326 are aligned with the toothed portion 644 on the outer surface 642 of the plunger engagement sleeve 614.

[0230] Distal movement of the plunger engagement post 618 from a disengaged state or position to an engaged state or position closes the receiving space 615 between the plunger engagement sleeve 614 and the plunger engagement post 618 to prevent removal of the one or more retaining members 368 of the plunger 326 from the receiving space 615. When the plunger engagement post 618 moves to the engaged position or position, the catch 374 of the at least one retaining member 368 of the plunger 326 is captured between the plunger engagement sleeve 614 and an outer surface 667 of the plunger engagement post 418 proximal to the locking rib 634. The piston 600 and connected plunger 326 can then reciprocate within the barrel 318 of the syringe 300. In some embodiments, the piston 600 can be advanced 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).

[0231] To unlock the syringe 300 from the syringe port of the injector and disengage the plunger 326 from the piston 600, the syringe 300 may be rotated clockwise or counterclockwise about the syringe longitudinal axis relative to the syringe port. Due to the alignment of one or more release tabs 380 on the plunger 326 with the toothed portion 644 on the plunger engagement sleeve 614, the rotation of the plunger 326 also rotates the plunger engagement sleeve. Because the plunger engagement post 618 is connected to the plunger engagement sleeve 614 via a rotation mechanism 671, the plunger engagement post 618 does not rotate with the rotation of 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.

[0232] When the retaining member 368 of the plunger 326 is disposed within 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 is opened to permit removal of the one or more retaining members 368 of the plunger 326 from the receiving space 615 by flexible distal movement of the catch 374 of the at least one retaining member 368 above the locking rib 634. To remove the plunger 326 from the piston 600, the syringe 300 can be pulled distally or the plunger 326 can be retracted proximally. During such relative movement of the piston 600 with respect to the plunger 326 away from each other, the catch 374 is biased above the locking rib 634 of the piston engagement sleeve 614 to permit removal of the one or more retaining members 368 from the piston 600.

[0233] 19-21B, a piston 700 and plunger engagement mechanism 712 according to another embodiment of the present disclosure are shown. The components of the piston 700 and plunger engagement mechanism 712 shown in FIGS. 19-21B are substantially similar or identical to the components of the piston 400 and plunger engagement mechanism 412 described herein with reference to FIGS. 9-13J. Accordingly, the reference numbers of FIGS. 19-21B are used to indicate the same components of the corresponding reference numbers in FIGS. 9-13J, except that the leading digits of the reference numbers used in FIGS. 19-21B are changed from "4" to "7". The above description of the piston 400 and plunger engagement mechanism 412 generally shown in FIGS. 9-13J is applicable to the piston 700 and plunger engagement mechanism 712 shown in FIGS. 19-21B, and therefore only the relative differences between the components shown in these figures are described below.

[0234] Referring initially 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. Piston 700 is reciprocatably movable within syringe port 16 in the direction of a longitudinal piston axis 720, such as via drive mechanism 402 shown in Figure 2.

[0235] 20, an exploded view of the piston 700 and 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 to be removably connected to a plunger of a syringe, such as the plunger 326 shown in FIGS. 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 from a transparent or translucent material configured to allow the passage of light emitted by one or more lights within the piston 700 to illuminate the plunger 326 and / or at least a portion of the syringe 300.

[0236] 20, the piston 700 has a sensing member 705, such as a pin 707 and a sensor 709. The pin 707 has a proximal end 713 configured to contact the sensor 709 when the distal end 715 of the pin 707 is forced proximally, such as by contact between the plunger 326 and the distal end 715 of the pin 707. The pin 707 can extend along a longitudinal axis 720 of the piston 700 and can protrude through at least a portion of the piston head 706. The pin 707 can operate to sense contact with a surface, such as a surface of the plunger 326, and can send one or more signals to the controller 200 (FIG. 2) to control movement of the piston 700 based on the sensed condition. For example, initial contact between the distal end 715 of the pin 707 and the plunger 326 can move the pin 707 proximally to contact the sensor 709. The sensor 709 may be operatively connected to the controller 200 such that upon actuation of the sensor 709 by the pin 707, the sensor 709 controls the movement of the drive mechanism of the piston 700. For example, the drive mechanism may be stopped or decelerated from a first speed to a second slower speed and the distal end 715 of the pin 707 and the plunger 326. The pin 707 may be biased to its distal position by a spring 711.

[0237] 20 , the plunger engagement mechanism 712 includes a plunger engagement sleeve 714 having a central opening 716 and a plunger engagement post 718. The plunger engagement post 718 is translatable along the direction of a longitudinal piston axis 720 relative to the plunger engagement sleeve 714 upon actuation of an actuator 722 (shown in FIGS. 21A-21B ). In some embodiments, the plunger engagement post 718 may be axially movable between an engaged position, in which the plunger 326 is locked in engagement with the piston 700 by capture of at least one retention member 368 of the plunger 326 between the plunger engagement sleeve 714 and the plunger engagement post 718, and a disengaged position, in which the plunger 326 may be removed from the piston 700.

[0238] 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 catch 374 of the at least one retaining member 368 of the plunger 326. The post portion 721 may be shaped to bias the at least one retaining member 368 radially outwardly due to contact of the catch 374 with an outer surface of the post portion 721 and / or the locking lip 729. In this manner, distal movement of the piston 700 relative to the plunger 326 biases the at least one retaining member 368 radially outwardly due to contact between the catch 374 and the post portion 721. In embodiments having multiple retaining members 368, each of the retaining members 368 is biased radially outward.

[0239] 20 , the plunger-engaging sleeve 714 has a hollow body 724, at least a portion of an outer surface of the hollow body 724 defining at least a portion of the piston head 706. A distal portion or end 726 of the plunger-engaging sleeve 714 is configured to be received in the internal cavity 340 (shown in FIG. 21A ) of the plunger 326, while at least a portion of the plunger 326, such as the 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-engaging sleeve 714.

[0240] A portion of the inner surface 728 of the central opening 716 at a distal end of the opening 716 may have a stepped inner diameter that decreases in diameter in a direction from the distal end of the plunger-engaging sleeve 714 to the proximal end of the plunger-engaging sleeve 714. For example, the opening 716 may have a first step 717 having a first inner diameter and a second step 719 disposed proximally of the first step 717 having a second diameter that is smaller than the first diameter of the first step 717. A ramp 730 may be provided between the first and second steps 717, 719 to bias at least one retention member 368 associated with the plunger 326 radially inward during connection of the plunger 326 to the distal portion or end 726 of the plunger-engaging sleeve 714.

[0241] Having described the structure of plunger 326 (see disclosure herein with reference to Figures 6-8C) and piston 700 according to one non-limiting embodiment of the present disclosure, the method of engagement and disengagement of plunger 326 from piston 700 will now be described with reference to Figures 21A-21B. A portion of syringe 300 is shown in Figures 21A-21B.

[0242] 21A shows piston 700 having plunger engagement mechanism 712 in a disengaged position or state and prior to locking engagement with plunger 326. In some embodiments, piston 700 may be advanced distally using drive mechanism 402 operated by controller 200 (FIG. 2). In another embodiment, the piston can be moved distally manually.

[0243] As the piston 700 may advance distally, the catch 374 on the at least one retaining member 368 of the plunger 326 is biased radially outward by contact with the locking lip 729 on the post portion 721. The plunger engagement post 718 is in its disengaged position and moves axially in a distal direction relative to the plunger engagement sleeve 714 such that the retaining member 368 may be biased radially outward into the space defined by the first step 717. After the catch 374 is disposed proximally against the locking lip 729, the at least one retaining member 368 may be resiliently biased in a radially inward direction, for example, due to the resilient flexibility of the retaining member 368 in combination with the ramped portion 730 between the first and second steps 717, 719. While the at least one retaining member 368 is in the position shown in FIG. 21A, the at least one retaining member 368 may be flexibly deflected radially outward with proximal movement of the piston 700 or distal movement of the plunger 326, as described herein (such as by removal of the syringe from the injector), such that the plunger 326 is not in locking engagement with the piston 700.

[0244] 21B, the plunger engagement post 718 moves from a disengaged position or state to an engaged position or state by moving proximally along the longitudinal piston axis 720. Such movement of the plunger engagement post 718 may result from de-energizing the actuator and allowing a resilient member, such as the resilient member 484 described herein with reference to FIGS. 9-13J, to axially urge the plunger engagement post 718 in the proximal direction, or by energizing the actuator to move the plunger engagement post 718 in the proximal direction. The proximal movement of the plunger engagement post 718 locks at least one of the retaining member 368 and the catch 374 within a space defined by the second shoulder 719 of the plunger engagement sleeve 714. Due to the smaller second diameter of the second step 719 in combination with the increased diameter of the locking lip 729, the 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 reciprocating axial movement of the piston 700 results in 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 of the plunger engagement post 718 in a distal direction, moving the locking lip 729 distally and allowing the catch 374 of the one or more retaining members 368 to move around the locking lip 729 of the first step 717, enabling removal of the one or more retaining members 368 of the plunger 326 from the receiving space 715 between the plunger engagement sleeve 714 and the plunger engagement post 718.

[0245] 22A-22E, a piston 800 and plunger engagement mechanism 812 according to another embodiment of the present disclosure are shown. The components of the piston 800 and plunger engagement mechanism 812 shown in FIGS. 22A-22E are substantially similar or identical to the components of the piston 400 and plunger engagement mechanism 412 described herein with reference to FIGS. 9-13J. Accordingly, the reference numbers of FIGS. 22A-22E are used to indicate the same components of the corresponding reference numbers in FIGS. 9-13J, except that the leading digits of the reference numbers used in FIGS. 22A-22E are changed from "4" to "8". The above description of the piston 400 and plunger engagement mechanism 412 generally shown in FIGS. 9-13J is applicable to the piston 800 and plunger engagement mechanism 812 shown in FIGS. 22A-22E, and therefore only the relative differences between the components shown in these figures are described below.

[0246] 22A, piston 800 has a body 804 and a piston head 806 at a distal end of body 804. Piston head 806 is configured to be removably connected to a plunger of a syringe, such as plunger 326 shown in FIG. 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 from a transparent or translucent material configured to allow the passage of light emitted by one or more lights 803 within piston 800 to illuminate plunger 326 and / or at least a portion of syringe 300.

[0247] The piston 800 has a sensing member 805, such as a sensing sleeve 807 and a sensor 809. The sensing sleeve 807 has a proximal end 813 configured to contact the sensor 809 when the distal end 815 of the sensing sleeve 807 is forced proximally, such as by contact between one or more retaining members 368 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 the piston 800 and may be recessed within the piston head 806. The sensing sleeve 807 may be operable to sense contact with a surface, such as a surface of the plunger 326, and the controller 200 may be signaled to control movement of the piston 800 based on the sensed condition. 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 the piston 800. Initial contact between the distal end 815 of the sensing sleeve 807 and one or more retention members 368 of the plunger 326 may retract the sensing sleeve 807 proximally such that the sensing sleeve 807 activates the sensor 809. The sensor 809 may be operatively connected to the controller 200 and to the drive mechanism of the piston 800 such that upon activation of the sensor 809 by the sensing sleeve 807, the sensor 809 signals the controller 200 to control movement of the drive mechanism. For example, the drive mechanism may be stopped or slowed down from a first speed to a second, slower speed. The sensing sleeve 807 may be biased to its distal position by a biasing member such as a spring 817.

[0248] The plunger engagement mechanism 812 includes a plunger engagement sleeve 814 having a central opening 816 and a plunger engagement post 818. The plunger engagement post 818 is translatable along the direction of the longitudinal piston axis 820 relative to the plunger engagement sleeve 814 upon actuation of an actuator, such as the actuator 422 described herein with reference to FIGS. 9-13J. In some embodiments, the plunger engagement post 818 may be axially movable between an engaged position in which the plunger 326 is locked in engagement with the piston 800 by capturing a locking rib 834 of the plunger engagement sleeve 814 and a catch 374 of the at least one retaining member 368 of the plunger 326 under the plunger engagement post 818, and a disengaged position in which the plunger 326 may be removed from the piston 800.

[0249] The plunger-engaging sleeve 814 has a hollow body 824, at least a portion of an outer surface of the hollow body 824 defining at least a portion of the piston head 806. A distal portion or end 826 of the plunger-engaging sleeve 814 is configured to be received in the internal cavity 340 of the plunger 326, while at least a portion of the plunger 326, such as the 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-engaging sleeve 814.

[0250] The 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 bias at least one retaining member 368 associated with the plunger 326 radially inward during connection of the plunger 326 to a distal portion or 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 a surface that engages with at least one catch 374 on the at least one retaining member 368 of the plunger 326 to prevent removal of the plunger 326 from the piston 800 when the plunger 326 is locked in engagement with the plunger engagement mechanism 812, as described herein.

[0251] Having described the structure of plunger 326 and piston 800 according to one non-limiting embodiment of the present disclosure, a method of engagement and disengagement of plunger 326 from piston 800 will now be described with reference to FIGS. 22A-22E.

[0252] 22A shows piston 800 having plunger engagement mechanism 812 in a disengaged position or state and prior to locking engagement with plunger 326. In some embodiments, piston 800 may be advanced distally using drive mechanism 402 operated by controller 200 (FIG. 2). In another embodiment, the piston can be moved distally manually.

[0253] 22A to 22B, as the piston 800 advances toward the plunger 326, the at least one retaining member 368 of the plunger 326 contacts the sensing sleeve 807 such that the sensing sleeve 807 moves proximally toward the sensor 809. The catch 374 on the at least one retaining member 368 of the plunger 326 is biased radially inward by contact with the locking rib 834 on the plunger engagement sleeve 814. The plunger engagement post 818 is in its disengaged position, e.g., retracted proximally. While the at least one retaining member 368 is in the position shown in FIG. 22B, the at least one retaining member 368 may be flexibly biased radially inward with proximal movement of the piston 800 or distal movement of the plunger 326 (such as by removal of the syringe from the injector), such that the plunger 326 is not in locking engagement with the piston 800.

[0254] 22C, when the sensing sleeve 807 moves proximally by contact with at least one retention member 368 of the plunger 326, the sensor 809 detects the presence of the sensing sleeve 807 and actuates the actuator 822 to move the plunger engagement post 818 axially in a distal direction from a disengaged position or state to an engaged position or state. Such movement of the plunger engagement post 818 may result from de-energizing the actuator 822. In another embodiment, movement of the plunger engagement post 818 may result from energizing an actuator 822, such as a solenoid, or by operation of a motor to move the actuator.

[0255] Movement of the plunger engagement post 818 from a disengaged state or position to an engaged state or position closes a receiving space 815 between the plunger engagement sleeve 814 proximal of the locking rib 834 and the plunger engagement post 818 to prevent removal of the catch 374 of the one or more retaining members 368 of the plunger 326 from the receiving space 815. When the plunger engagement post 818 moves to an engaged position or position, the catch 374 of the at least one retaining member 368 of the plunger 326 is captured between the locking rib 834 of the plunger engagement sleeve 814 and the plunger engagement post 818. The piston 800 and connected plunger 326 can then reciprocate within the barrel 318 of the syringe. In some embodiments, the piston 800 can be advanced 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).

[0256] 22D, to unlock the plunger 326 from the plunger engagement mechanism 812, the plunger engagement post 818 is moved to a disengaged position via axial movement in a distal direction, for example by stored restoring force from an actuator (described herein) or a biasing member, allowing removal of one or more retention members 368 of the plunger 326 from the receiving space 815 between the plunger engagement sleeve 814 and the plunger engagement post 718. Removal of the plunger 326 from the piston 800 allows the sensing sleeve 807 to move distally due to the restoring force provided by the spring 817 (FIG. 22E).

[0257] 23A-23G, a piston 900 and plunger engagement mechanism 912 are shown in accordance with another embodiment of the present disclosure. Certain components of the piston 900 and plunger engagement mechanism 912 shown in FIGURES 23A-23G are substantially similar or identical to components of the piston 400 and plunger engagement mechanism 412 described herein with reference to FIGURES 9-13J. Certain features of the foregoing description of the piston 400 and plunger engagement mechanism 412 generally shown in FIGURES 9-13J are applicable to the piston 900 and plunger engagement mechanism 912 shown in FIGURES 23A-23G, and therefore only the relative differences between the components shown in those figures will be described below.

[0258] 23A, the plunger 326 has at least one retaining member 368 having a catch 374 that projects radially outward relative to the plunger longitudinal axis 334. The catch 374 is configured to be received within at least a portion of the piston engagement feature 912. In some embodiments, the catch 374 has a rounded or angled catch surface 375 that is angled at an acute or obtuse angle relative to the plunger longitudinal axis 334. The angled catch surface 375 is configured to contact at least a portion of the plunger engagement feature 912 during engagement of the plunger 326 with the piston 900, as described herein. The at least one retaining member 368 can also have at least one rounded or angled release surface 369. The angled release surface 369 may be provided on at least a portion of the catch 374, such as opposite the angled catch surface 375. The rounded or angled release surface 369 is angled at an acute or obtuse angle relative to the plunger longitudinal axis 334 in a direction opposite to the arc or angle of the rounded or angled catch surface 375. The rounded or angled release surface 369 is configured to interact with at least a portion of the plunger engagement feature 912 during disengagement of the plunger 326 from the piston 900, as described herein. In various embodiments, the friction or locking interaction between the rounded or angled release surfaces 369b without additional support is insufficient to lockably engage the plunger 326 with the plunger engagement feature 912 of the piston 900.

[0259] The piston 900 is extendable and retractable from the housing of the fluid injector 10, 100 (FIGS. 1 and 3). The piston 900 includes a stem 901 and a piston head 920 formed at a distal end of the stem 901. In certain embodiments, the piston head 920 may extend radially outward beyond a radial edge of the stem 901. The piston head 920 may be a substantially cylindrical structure having a piston cavity 940 configured to receive at least a portion of the plunger 326, such as at least one retaining member 368, when the plunger 326 is connected with the piston 900. The piston cavity 940 may have at least one locking lip 950 projecting radially inward from an inner surface of the piston cavity 940. The at least one locking lip 950 is configured to engage at least a portion of the retaining member 368, such as the catch 374. The at least one locking lip 950 may be circumferentially continuous or discontinuous about the piston cavity 940 .

[0260] In some examples, at least one locking lip 950 has a rounded or angled distal surface 960 and a rounded or angled proximal surface 970. The rounded or angled distal surface 960 is arcuate or angled in the same direction as the rounded or angled catch surface 375 of the plunger 326. In this manner, the distal surface 960 engages with the catch surface 375 during the connection process between the piston 900 and the plunger 326 to flexibly and resiliently deflect the one or more retention members 368 in a radially inward direction toward the plunger longitudinal axis 334 to allow the plunger 326 to be inserted into the piston cavity 940. The rounded or angled proximal surface 970 is arcuate or angled in the opposite direction to the rounded or angled distal surface 960. The rounded or angled proximal surface 970 is arcuate or angled in the same direction as the rounded or angled release surface 369 of the plunger 326. In this manner, the proximal surface 970 engages the release surface 369 when the piston 900 and / or plunger 326 are moved axially to disengage the plunger 326 from the piston 900. The engagement between the release surface 369 on the plunger 326 and the proximal surface 970 of the piston 900 biases the one or more retention members 368 radially inward toward the longitudinal axis 334 to allow the plunger 326 to be withdrawn from the piston cavity 940.

[0261] 23A-23G, the piston 900 has a locking member 980 configured to lock the plunger 326 relative to the piston 900. The locking member 980 may be axially movable between a first position (FIG. 23D) and a second position (FIG. 23E). In some examples, the locking member 980 is movable to extend at least partially into the piston cavity 940. When extended in the second position, the locking member 980 is inserted into the cavity 340 of the plunger 326 to prevent radially inward deflection of the at least one retaining member 368. For example, in the second engagement position, the locking member 980 locks the catch 374 relative to the at least one locking lip 950 by holding the release surface 369 of the plunger 326 against the proximal surface 970 of the piston 900 such that the catch 374 cannot move beyond the at least one locking lip 950. In some embodiments, a sensing member (not shown), such as a spring pin connected to a sensor, may be provided to detect contact with a surface, such as the surface of plunger 326, and movement of piston 900 may be controlled based on the detected condition.

[0262] Having described the structure of plunger 326 and piston 900 according to one non-limiting embodiment, the engagement and disengagement of plunger 326 with respect to piston 900 will now be described with reference to Figures 23A-G. The syringe 12 shown in Figure 23A has been omitted from the remainder of Figures 23B-G for clarity.

[0263] To engage the plunger 326 with the piston 900, the syringe 12 is first connected to the syringe port 16 of the fluid injector 10 (FIG. 1) or pressure jacket 15 (FIG. 3). Once the syringe 12 is inserted into the syringe port 16, various locking mechanisms (not shown) may be used to retain the syringe 12 within the syringe port 16 or within the pressure jacket to prevent separation of the syringe 12 from the syringe port 16. Initially, the plunger 326 may be disposed at the proximal end 20 of the syringe barrel 18. The piston 900 may then be advanced distally toward the plunger 326 for engagement of the piston head 920 with the plunger 326.

[0264] 23A-23B, the piston 900 advances axially in a distal direction (arrow A in FIGS. 23A-23B) such that the angled distal surface 960 of the piston head 920 contacts the at least one retaining member 368 of the plunger 326. Initially, the angled distal surface 960 contacts a catch 374, such as catch face 375 of the at least one retaining member 368. Because the catch 374 projects radially outward relative to the at least one retaining member 368, the catch 374 is disposed at a greater radial distance from the plunger longitudinal axis 334 than the inner surface of the piston cavity 940 proximal to the angled distal surface 960. In this manner, continued distal movement of the piston 900 flexibly and resiliently deflects the at least one retaining member 368 radially inward due to contact between the catch face 375 of the plunger 326 and the distal surface 960 of the piston 900 (FIG. 23B). In examples having multiple retaining members 368 , each of the retaining members 368 is biased radially inward relative to the plunger longitudinal axis 334 .

[0265] 23C, during continued axial movement of the piston 900 in the distal direction, the catch 374 advances axially beyond the at least one lip 950 of the piston head 920. A restoring force generated during radial deflection of the flexible at least one retaining member 368 causes the catch 374 to snap radially outwardly into a proximally disposed recess 990 of the at least one locking lip 950 (FIG. 23A). Thus, the plunger 326 is releasably retained within the piston cavity 940. To lock the plunger 326 to the piston 900 and prevent removal of the plunger 326 from the piston 900, the locking member 980 is extended from a first position (FIG. 23D) to a second position (FIG. 23E) by moving the locking member 980 radially (arrow B). In the second position, the locking member 980 is positioned such that the retaining member 368 is locked between the inner surface of the piston cavity 940 and the outer surface of the locking member 980 and cannot flexibly deflect inwardly to disengage. The locking member 980 prevents the retaining member 368 from moving in a radially inward direction, thereby preventing the plunger 326 from disengaging from the piston 900. In this manner, the piston 900 can move in a proximal or distal direction, resulting in a corresponding movement of the plunger 326. The locking member 980 can be moved between the disengaged and engaged positions by an electromechanical actuator, such as a solenoid actuator, a rotary motor, a linear motor, or the like. As shown in FIGS. 23A-B, the locking member 980 can be reciprocated using a rotary motor to rotate the mating surfaces of a threaded screw drive.

[0266] To unlock the syringe 12 from the syringe port 16 and disengage the plunger 326 from the piston 900, the locking member 980 moves from the second position to the first position by moving axially in the direction of arrow C in FIG. 23F. With the locking member 980 in the first position, the plunger 326 can be disengaged from the piston 900 by moving the plunger 326 distally (arrow D in FIG. 23G) through the syringe 12 and / or by moving the piston 900 proximally. Such relative movement between the piston 900 and the plunger 326 engages the angled release surface 369 of the retaining member 368 with the angled proximal surface 970 of the piston 900. Continued movement of the plunger 326 away from the piston 900 biases the retaining member 368 radially inward to remove the lip 950. After removing lip 950 , retaining member 368 springs radially outward, thereby completely disengaging plunger 326 from piston 900 .

[0267] 24A-24C, a piston 1000 and plunger engagement mechanism 1012 according to another embodiment of the present disclosure are shown. The components of the piston 1000 and plunger engagement mechanism 1012 shown in FIGS. 24A-24C are substantially similar or identical to the components of the piston 400 and plunger engagement mechanism 412 described herein with reference to FIGS. 9-13J. Accordingly, the reference numbers of FIGS. 24A-24C are used to indicate the same components of the corresponding reference numbers in FIGS. 9-13J, except that the leading digits of the reference numbers used in FIGS. 24A-24C are changed from "4" to "10". The above description of the piston 400 and plunger engagement mechanism 412 generally shown in FIGS. 9-13J is applicable to the piston 1000 and plunger engagement mechanism 1012 shown in FIGS. 24A-24C, and therefore only the relative differences between the components shown in these figures are described below.

[0268] 24B, the plunger engagement mechanism 1012 has a plunger engagement sleeve 1014 having a central opening 1016 and a plunger engagement post 1018 reciprocally movable within the central opening 1016 of the plunger engagement sleeve 1014 along the direction of the longitudinal piston axis 1020. The plunger engagement post 1018 is reciprocally driven by an actuator, such as the actuator 422 described herein with reference to FIG. 9 or another embodiment 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 disposed within the plunger engagement sleeve 1014 to capture at least one retention member 368 associated with the plunger 326 within a receiving space 1015 between the plunger engagement sleeve 1014 and the plunger engagement post 1018 (shown in FIG. 24C). Conversely, in the disengaged position or state, the plunger engagement post 1018 may be positioned relative to the plunger engagement sleeve 1014 to permit 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.

[0269] 24B, the plunger-engaging sleeve 1014 has a hollow body 1024, at least a portion of an outer surface of the hollow body 1024 defining at least a portion of the piston head 1006. A distal portion or end 1026 of the plunger-engaging sleeve 1014 is configured to be received in the internal cavity 340 of the plunger 326, while at least a portion of the plunger 326, such as the 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-engaging sleeve 1014. The outer surface 1042 of the plunger-engaging sleeve 1014 can 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.

[0270] The plunger-engaging sleeve 1014 further includes at least one locking groove 1065 recessed into an inner surface of the central opening 1016. In some embodiments, the at least one groove 1065 may be configured to receive a catch 374 of the at least one retaining member 368 of the plunger 326 when the plunger 326 is connected to the plunger-engaging sleeve 1014.

[0271] The plunger engagement post 1018 has a shaft 1072 having a proximal end 1074 and a distal end 1076. The distal end 1076 of the shaft 1072 has a tapered end surface 1078 configured to contact the 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 to the engaged position, the plunger engagement post 1018 prevents removal of the plunger 326 from the piston 1000 (shown in FIG. 24C ), for example, by locking the catch 374 of the at least one retaining member 368 of the plunger 326 under the locking groove 1065 of the plunger engagement sleeve 1014. The proximal end 1074 of the shaft 1072 is configured to connect to an actuator, similar to the actuator 422 described herein with reference to Figures 9-13J, for moving the plunger engagement post 1018 relative to the plunger engagement sleeve 1014 between an engaged position or state and a disengaged position or state.

[0272] 24C, the proximal end 1074 of the shaft 1072 is received in a rotation mechanism 1071 slidably mounted within the hollow body 1024 of the plunger engagement sleeve 1014. In some embodiments, the rotation mechanism 1071 may be configured to rotate in one direction, such as a clockwise or counterclockwise direction, about the longitudinal piston axis 1020, as described according to various embodiments herein. For example, the rotation mechanism 1071 may be a one-way clutch.

[0273] Having described the structure of the plunger 326 and piston 1000 according to one non-limiting embodiment of the present disclosure, a method of engagement and disengagement of the plunger 326 with respect to the piston 1000 will now be described.

[0274] FIG. 24C illustrates the piston 1000 with its plunger engagement feature 1012 in an engaged position or state with the plunger 326. As described herein with reference to FIGS. 13A-13J, the plunger 326 can be connected to the piston 1000 by moving the piston 1000 distally to allow insertion of one or more retention members 368 of the plunger 326 into the receiving space 1015 between the plunger engagement sleeve 1014 and the plunger engagement post 1018 such that the catch 374 is in the locking groove 1065. In some embodiments, the piston 1000 can be advanced distally using a drive mechanism 402 operated by the controller 200 (FIG. 2). In another embodiment, the piston 1000 can be moved distally manually.

[0275] The piston 1000 advances axially in the distal direction such that at least one retaining member 368 of the plunger 326 is received within the central opening 1016 of the plunger engaging sleeve 1014 such that the at least one retaining member 368 is biased radially inward by contact between the catch 374 and the inner surface of the plunger engaging sleeve 1014. In embodiments having multiple retaining members 368, each of the retaining members 368 is biased radially inward.

[0276] During continued axial movement of the piston 1000 in the distal direction, the catch 374 is biased radially outward into the locking groove 1065 of the piston engagement sleeve 1014. After the catch 374 is disposed in the locking groove 1065, distal movement of the piston 1000 relative to the plunger 326 is stopped, such as by engagement between the toothed portion 329 of the plunger 326 and the toothed portion 1044 of the outer surface 1042 of the plunger engagement sleeve 1014. The plunger engagement post 1018 is in a disengaged position or state, the plunger 326 is connected to the piston 1000, and the toothed portion 329 on the plunger 326 is aligned with the toothed portion 1044 on the outer surface 1042 of the plunger engagement sleeve 1014.

[0277] Movement of the plunger engagement post 1018 from a disengaged state or position to an engaged state or position closes the receiving space 1015 between the plunger engagement sleeve 1014 and the plunger engagement post 1018 to prevent removal of the one or more retaining members 368 of the plunger 326 from the receiving space 1015 and the locking groove 1065. When the plunger engagement post 1018 moves to the engaged position or position, the at least one retaining member 368 of the plunger 326 is captured between the plunger engagement sleeve 1014 and the outer surface of the plunger engagement post 418. The piston 1000 and connected plunger 326 can then reciprocate within the barrel 318 of the syringe 300. In some embodiments, the piston 1000 can be advanced 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).

[0278] To unlock the syringe 300 from the syringe port of the injector and disengage the plunger 326 from the piston 1000, the syringe 300 is rotated clockwise or counterclockwise about the syringe longitudinal axis relative to the syringe port. Due to the alignment of the toothed portion 329 on the plunger 326 with the toothed portion 1044 on the plunger engagement sleeve 1014, the rotation of the plunger 326 also rotates the plunger engagement sleeve 1014. Because the plunger engagement post 1018 is connected to the plunger engagement sleeve 1014 via a rotation mechanism 1071, the plunger engagement post 1018 does not rotate with the rotation of the plunger engagement sleeve 1014. In some embodiments, the plunger engagement post 1018 may be movable between an engaged position and a disengaged position via an actuator, such as the actuator 424 described herein with reference to FIGS. 9-13J.

[0279] 25A and 25B show an embodiment of a piston-plunger engagement system according to another embodiment. FIG. 25A shows the system in a disengaged position where the plunger includes radially inwardly facing opposing engagement flanges or catches 2774 extending proximally from an inner surface of the plunger base. The piston includes at least one flexible retaining member 2750 having at least one retention catch 2755 configured to engage with a corresponding engagement flange or catch 2774 of the plunger base. In the disengaged position, the movable locking member 2798 is configured in a distal first position such that the locking member 2798 does not engage the at least one flexible retaining member 2750 of the piston 2700. As shown in FIG. 25B, the piston-plunger engagement system is in an engaged position and the movable locking member 2798 is moved proximally, for example, by a motor, solenoid, or cam system. As the locking member 2798 moves proximally, the proximal surface 2799, e.g., an angled surface as shown in FIGS. 25A and 25B, contacts and engages the at least one flexible retaining member 2750 causing the retaining member 2750 to bend in a radially outward direction. As the retaining member 2750 moves radially outward, the at least one retaining catch 2755 engages the at least one radially inward facing engaging flange or catch 2774 to lock the plunger base to the piston. Generally, the at least one radially inward facing engaging flange or catch 2774 is substantially inflexible due, for example, to the structural strength or outer surface of the plunger engaging sleeve 2714 which prevents the engaging flange or catch 2774 from bending radially outwardly and dislodging from the at least one retaining catch 2755 of the at least one flexible retaining member 2750. Moving the locking member 2798 distally releases the force applied to the at least one flexible retaining member 2750, allowing the retaining member 2750 to return to a non-bent, disengaged position such that the at least one retaining catch 2755 does not contact or engage with the at least one radially inward facing opposing engagement flange or catch 2774, allowing the plunger to be removed from the piston.

[0280] In some embodiments, the resilient elastic member 2784 may be configured to bias the locking member 2798 toward a disengaged or engaged position. For example, the resilient elastic member 2784 may be a compression spring configured to bias the locking member 2798 in a distal direction toward the disengaged position. In this manner, the locking member 2798 is normally in a disengaged state such that the plunger can be disengaged from the locking member 2798 in the event of a power loss. In another embodiment, the resilient elastic member 2784 may be a tension spring configured to bias the locking member 2798 in a proximal direction toward the engaged position. In such an embodiment, the locking member 2798 is normally in an engaged position and must be moved to a disengaged position, such as using the actuator 422 described herein with reference to FIG. 9 to allow removal of the plunger from the locking member 2798.

[0281] Referring to FIG. 26, a piston 1100 having a plunger engagement mechanism 1112 according to another embodiment of the present disclosure is shown. In some embodiments, the piston 1100 may be configured for use with the injectors 10, 100 shown in FIG. 1 and FIG. 3. In another embodiment, the piston 1100 may be configured for use with any fluid injector configured for medical applications, such as injection of contrast media and saline in contrast imaging procedures. The piston 1100 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 (FIG. 2), a hydraulic system, a pneumatic system, or any combination thereof. The controller 200 (FIG. 2) may be configured to control the operation of the drive mechanism, and thus the reciprocating movement of the piston 1100.

[0282] The piston 1100 has a body 1104 and a piston head 1106 at a distal end of the body 1104. The piston head 1106 is configured to be removably connected to the plunger 326 of the syringe 300. The piston head 1106 has a substantially cylindrical structure with a partially conical distal end configured to be received inside at least a portion of the internal cavity 340 of the plunger 326. In some embodiments, at least a portion of the piston head 1106 and / or the plunger 326 may be made from a transparent or translucent material configured to allow the passage of light emitted by one or more lights within the piston 1100 to illuminate the plunger 326 and / or at least a portion of the syringe 300.

[0283] 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 rapid removal of the syringe 300 and plunger 326 from the piston head 1106 and fluid injector at the end of an injection procedure. The plunger engagement mechanism 1112 has a plunger engagement sleeve 1114 having a central opening 1116 and a plunger engagement post 1118 reciprocally movable within the central opening 1116 of the plunger engagement sleeve 1114 along the direction of a longitudinal piston axis 1120. The plunger engagement post 1118 is reciprocally driven 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 an engaged position or state, the plunger engagement post 1118 may be positioned within the plunger engagement sleeve 1114 to capture at least one retention member 368 associated with the plunger 326 within a receiving space 1115 between the plunger engagement sleeve 1114 and the plunger engagement post 1118. Conversely, in a disengaged position or state, the plunger engagement post 1118 may be positioned relative to the plunger engagement sleeve 1114 to permit removal of the at least one retention member 368 associated with the plunger 326 from the receiving space 1115 between the plunger engagement sleeve 1114 and the plunger engagement post 1118.

[0284] The actuator 1122 may be configured to have an engaged state for moving one of the plunger engagement sleeve 1114 and the plunger engagement post 1118 to an engaged position and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement post to a disengaged position. In some embodiments, the actuator 1122 may be automatically moved to the disengaged state, such as during a loss of power to the actuator 1122. In some embodiments, the actuator 1122 may be in an engaged state only during proximal movement of the piston 1100. In some embodiments, the actuator 1122 may be a solenoid configured to be primarily in a disengaged state and may be in an engaged state only during connection of the plunger 326 to the piston 1100. In another embodiment, the actuator 1122 may be a rotary electric motor, a linear electric motor, or a linear actuator. In some embodiments, the actuator 1122 is a linear actuator that can be manually back-driven in the event of a loss of power to the injector. In various embodiments, moving one of the plunger engagement sleeve 1118 and the plunger engagement post 1118 to a disengaged state for removal of the plunger 326 from the piston 1100 may be accomplished by rotation of the plunger 326 relative to the piston 1100, as described herein.

[0285] With reference to FIG. 27A, a plunger-engaging sleeve 1114 according to one embodiment is described. The plunger-engaging sleeve 1114 has a hollow body 1124, at least a portion of an outer surface of the hollow body 1124 defining at least a portion of the piston head 1106 (FIG. 26). In some embodiments, a distal portion or end 1126 of the hollow body 1124 may have a conical shape configured to correspond to a shape of the internal cavity 340 of the conical shaped 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 in the central opening 1116. The central opening 1116 extends through the hollow body 1124 of the plunger-engaging sleeve 1114. A proximal end or portion 1132 of the hollow body 1124 may be configured to be received in a plunger release sleeve 1158 (shown in FIG. 28).

[0286] 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 tabs 380 on the plunger 326 during installation 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 protruding from the outer surface 1142. The one or more plunger release teeth 1145 may protrude radially outward from the outer surface 1142 of the hollow body 1124. The one or more plunger release teeth 1145 are separated from one another 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 where three or more plunger release teeth 1145 are provided, the plunger release teeth 1145 may be evenly spaced from one another. In some embodiments, the plunger release teeth 1145 may have a non-uniform angular spread and / or a non-uniform angular spacing. The radial spacing of the plunger release teeth 1145 may be selected to correspond to the spacing between the one or more release tabs 380 on the plunger 326. The distal end 1147 of each of the plunger release teeth 1145 can have a tip 1149 configured to self-orient and guide the one or more release tabs 380 on the plunger 326 during connection of the plunger 326 to the plunger engagement sleeve 1114. As described herein, the one or more plunger release teeth 1145 are configured to interact with the one or more release tabs 380 on the plunger 326 to cause release of the plunger 326 from the piston upon rotation of the plunger 326 about its longitudinal axis 334, such as by rotation of the syringe 300.

[0287] 27B, a portion of the inner surface 1128 of the central opening 1116 at a distal end of the opening 1116 can have a tapered portion 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 end 1132. In some embodiments, the tapered portion 1130 can 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 end 1126 of the plunger-engaging sleeve 1114. In another embodiment, the tapered portion 1130 can define a clearance space for at least a portion of the at least one retaining member 368, such as the catch 374, during connection of the plunger 326 to the plunger-engaging sleeve 1114. The inner surface 1128 of the central opening 1116 may have a tapered inner diameter that decreases in a 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 proximal to the ramp 1130 and a second diameter smaller than the first diameter distal to the ramp 1130. The inner surface 1128 of the central opening 1116 may be substantially cylindrical proximal to the ramp 1130. In another embodiment, one or both portions of the inner surface 1128 before and after the ramp 1130 may have a slight slope sloping in the same direction as the ramp 1130.

[0288] 26 and 28, the plunger release sleeve 1158 surrounds at least a portion of the 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 the proximal end or portion 1132 of the plunger engagement sleeve 1114. In some embodiments, the plunger release sleeve 1158 has a cylindrical sidewall 1160 with an opening 1162 extending therethrough. The opening 1162 can have a longitudinal surface 1163 that is substantially parallel to the longitudinal axis 1164 of the plunger release sleeve 1158 and an inclined surface 1166 adjacent the longitudinal surface 1163 and inclined relative to the longitudinal axis 1164 of the plunger release sleeve 1158 in a direction from the distal end 1168 toward the proximal end 1170. As described herein, the longitudinal surface 1163 is configured to guide the guide pin 1139 associated with the plunger engagement post 1118 during movement of the plunger engagement post 1118 longitudinally along the longitudinal axis 1120 of the piston 1100, while the inclined surface 1164 is configured to guide the guide pin 1139 to move the plunger engagement post 1118 during rotational movement of the plunger 326 relative to the piston 1100, such as during removal of the plunger 326 from the piston 1100.

[0289] 29, the plunger engagement mechanism 1112 further includes a housing 1146 configured to receive the actuator 1122. The housing 1146 has a proximal portion 1152 connected to a distal portion 1154. In some embodiments, the distal portion 1154 may have a smaller outer diameter than the proximal portion 1152 such that a ledge 1156 is defined at the transition between the proximal portion 1152 and the distal portion 1154. In some embodiments, the ledge 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 the plunger release sleeve 1158.

[0290] 26, the plunger engagement sleeve 1114 and the plunger release sleeve 1158 are fixed against rotation relative to one another, but are both rotatable about the longitudinal piston axis 1120 relative to the plunger engagement post 1118 between a first position and a second position, as described herein with reference to FIGS. 30A-30D. In some embodiments, the plunger engagement sleeve 1114 and the plunger release sleeve 1158 may be rotatable in one of a clockwise and counterclockwise direction, or a clockwise and counterclockwise direction. The plunger engagement sleeve 1114 and the plunger release sleeve 1158 may be rotatable from a first position to a second position by rotational movement of the plunger 326 about the longitudinal piston axis 1120. For example, the plunger engagement sleeve 1114 and the plunger release sleeve 1158 may be rotatable about the longitudinal axis 1120 due to interaction of a release tab 380 on the plunger 326 with a toothed portion 1144 on the piston engagement sleeve 1114. The biasing member 1196 may be configured to bias the plunger engagement sleeve 1114 and the plunger release sleeve 1158 toward the first position. In this manner, as the plunger engagement sleeve 1114 and the plunger release sleeve 1158 are rotated from the first position toward the second position, the biasing member 1196 builds potential energy that is then used to assist in returning the plunger engagement sleeve 1114 and the plunger release sleeve 1158 toward the first position.

[0291] 29, the plunger engagement post 1118 is shown separate from the plunger engagement feature 1112. The plunger engagement post 1118 has a shaft 1172 having a proximal end 1176 and a distal end 1174. The proximal end 1176 of the shaft 1172 is connected to the 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 the at least one retaining member 368 radially outward as it passes by the end face 1178. A seal 1180 (FIG. 26) may be provided at the proximal end 1176 for sealing against the inner surface 1128 of the plunger engagement sleeve 1114. The seal 1180 may be an O-ring seal.

[0292] 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 disposed substantially perpendicular to the longitudinal axis 1120 of the plunger engagement post 1118.

[0293] The plunger engagement post 1118 has a locking groove 1127 configured to receive a catch 374 of the at least one retaining member 368 of the plunger 326. The end face 1178 may be shaped to bias the at least one retaining member 368 radially outwardly due to contact of the catch 374 with an outer surface of the end face 1178. In this manner, distal movement of the piston 1100 relative to the plunger 326 biases the at least one retaining member 368 radially outwardly due to contact between the catch 374 and the rounded or tapered outer surface of the end face 1178.

[0294] The plunger engagement post 1118 has a sensing member 1105, such as a pin 1107 and a sensor 1109. The pin 1107 has a proximal end 1113 configured to contact the sensor 1109 when the distal end 1117 of the pin 1107 is forced proximally, such as by contact between the plunger 326 and the distal end 1117 of the pin 1107. The pin 1107 can extend along a longitudinal axis 1120 of the piston 1100 and can protrude through at least a portion of the piston head 1106. The pin 1107 can operate to sense contact with a surface, such as an inner surface of the plunger 326, and can send one or more signals to the fluid injector controller 200 to control movement of the piston 1100 based on the sensed condition. For example, initial contact between the distal end 1117 of the pin 1107 and the plunger 326 can retract the pin 1107 proximally to activate the sensor 1109. The sensor 1109 may be operatively connected to a controller 200 that controls the drive mechanism of the piston 1100 such that upon actuation of the sensor 1109 by the pin 1107, the sensor 1109 controls movement of the drive mechanism. For example, the drive mechanism may be stopped or slowed down from a first speed to a second, slower speed. The pin 1107 may be biased to its distal position by a spring 1111. A seal 1119 may be provided between the pin 1107 and the plunger engagement post 1118 to prevent ingress of fluid.

[0295] 29, one or more lights 1173 may be provided on a printed circuit board 1175 on the base of the plunger engagement post 1118. The one or more lights 1173 may be configured to illuminate at least a portion of the plunger 326 and the plunger engagement sleeve 1114, as described herein.

[0296] Having described the structure of the plunger 326 and piston 1100 according to one non-limiting embodiment of the present disclosure, the method of engagement of the plunger 326 to the piston 1100 will now be described with reference to Figures 30A-30D. Figures 31A-31D show the plunger engagement mechanism 1112 at various stages of disengagement of the plunger 326 from the piston 1100.

[0297] FIG. 30A shows the piston 1100 with its plunger engagement mechanism 1112 in a disengaged position or state and prior to connection with the plunger 326. In some embodiments, the default state of the plunger engagement mechanism 1112 may be an engaged position or state. In another embodiment, the default 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 connection of the syringe 300 to the injector, the piston 1100 is retracted into the housing of the injector. After connecting the syringe 300 to the injector, the piston 1100 can be advanced distally within the bore of the syringe 300 toward the plunger 326.

[0298] 30A, the actuator 1122 (shown in FIG. 26) is actuated to a disengaged position or condition and the plunger engagement post 1118 is disposed in its distal position. Movement of the plunger engagement post 1118 in a distal direction opens the receiving space 1115 between the plunger engagement sleeve 1114 and the plunger engagement post 1118 to permit insertion of one or more retention members 368 of the plunger 326 into the receiving space 1115. The pin 1107 is in its distal position while the guide pin 1139 is at the distal end 1151 of the longitudinal surface 1163 of the opening 1162 (FIG. 28) on the plunger release sleeve 1158.

[0299] 30B, the piston 1100 is moved axially in a distal direction toward the plunger 326 (indicated by arrow A1). In some embodiments, the piston 1100 may be advanced distally using a drive mechanism 402 operated by the injector's controller 200 (FIG. 2). In another embodiment, the piston may be moved distally manually. The piston 1100 is advanced axially in a distal direction such that at least one retention member 368 of the plunger 326 is received within a central opening 1116 of the plunger engagement sleeve 1114. As the piston 1100 advances distally toward the plunger 326, at least a portion of the one or more retention members 368 on the plunger 326 contacts a tapered end surface 1178 of the plunger engagement post 1118, thereby flexibly deflecting the retention members 368 in a radially outward direction. For example, the catch 374 projects radially inward relative to the second end of the retaining member 368 such that the catch 374 contacts the tapered surface 1178 of the plunger engagement post 1118, thereby biasing the retaining member 368 in a radially outward direction. In embodiments having multiple retaining members 368, each of the retaining members 368 is biased radially outward.

[0300] 30C, during continued axial movement of the piston 1100 in the distal direction, the retaining members 368 are positioned such that the catches 374 can be deflected into the locking grooves 1127 of the piston engagement posts 1118. After the catches 374 are positioned in the locking grooves 1127, the at least one retaining member 368 can be resiliently deflected in a radially inward direction such that the retaining members 368 can move up the ramp 1130 of the inner surface 1128 of the central opening 1116 into a second diameter of the inner surface 1128. While the at least one retaining member 368 is in the position shown in FIG. 30C, the at least one retaining member 368 can be deflected radially outward with proximal movement of the piston 1100 or distal movement of the plunger 326 (such as by removal of the syringe from the injector) such that the plunger 326 is not in locking engagement with the piston 1100 and the catches 374 can emerge from the locking grooves 1127. With the plunger 326 connected to the piston 1100, one or more release tabs 380 on the plunger 326 align with 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 the proximal direction upon contact with the plunger 326 such that the proximal end 1113 of the pin 1107 can be detected by the sensor 1109, signaling the controller 200 to stop further distal movement of the piston 1100.

[0301] 30D, the actuator 1122 (FIG. 26) is operated to move the plunger engagement post 1118 from a disengaged position or state to an engaged position or state in a proximal direction indicated by arrow B1. Distal movement of the plunger engagement post 1118 closes the receiving space 1115 between the plunger engagement sleeve 1114 and the plunger engagement post 1118 which locks the catch 374 in the locking groove 1127 to prevent one or more retention members 368 of the plunger 326 from disengaging and emerging from the receiving space 1115. As the plunger engagement post 1118 moves to the engaged position or state, at least one retention member 368, including the catch 374, of the plunger 326 is captured between the plunger engagement sleeve 1114 and the plunger engagement post 1118 such that axial movement of the piston 1100 results in corresponding axial movement of the plunger 326 within the syringe barrel. As the plunger engagement post 1118 moves proximally, the guide pin 1139 moves axially distally from the distal end 1151 to the proximal end 1153 of the longitudinal face 1163 of the opening 1162 (FIG. 28) on the plunger release sleeve 1158.

[0302] The piston 1100 and connected plunger 326 can then reciprocate within the barrel 318 of the syringe 300. In some embodiments, the piston 1100 can be advanced 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).

[0303] 31A-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 may be rotated clockwise or counterclockwise about the syringe longitudinal axis 315 (FIG. 5B) relative to the syringe port. Because the plunger 326 is substantially free of rotation within the syringe barrel 318 due to the frictional contact therebetween, rotation of the syringe 300 also rotates the plunger 326 relative to the piston 1100 about the longitudinal piston axis 1120. Due to the alignment of one or more release tabs 380 on the plunger 326 with the plunger release teeth 1145 on the toothed portion 1144 of the plunger engagement sleeve 1114, rotation of the plunger 326 also rotates the plunger engagement sleeve 1114 and the plunger release sleeve 1158 from a first position to a second position relative to the plunger engagement post 1118. 31A (e.g., from a proximal end of the ramp 1166 toward a distal end of the ramp 1166).

[0304] 31A, movement of the guide pin 1139 along the angled surface 1166 of the plunger release sleeve 1158 causes the plunger engagement post 1118 to move axially in the distal direction of arrow C1 from an engaged position or state to a disengaged position or state. Movement of the plunger engagement post 1118 in the distal direction opens the receiving space 1115 between the plunger engagement sleeve 1114 and the plunger engagement post 1118 to permit distal movement of the one or more retention members 368 of the plunger 326 from the receiving space 1115 (see FIG. 31B).

[0305] When the plunger engagement mechanism 1112 is in a disengaged position or state, the syringe 300 can be pulled distally or the piston 1100 can be retracted proximally to remove the plunger 326 from the piston 1100. During such relative movement of the piston 1100 relative to the plunger 326 away from one another, the catch 374 of each of the at least one retaining member 368 engages with the plunger engagement post 1118 distal of the locking groove 1127 such that each retaining member 368 is flexibly biased 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 away from the piston 1100, as shown in FIG. 31D, allowing removal of the syringe 300 from the injector port.

[0306] 31D , after the plunger 326 is removed from the piston 1100, the plunger engagement sleeve 1114 and the plunger engagement post 1118 are automatically rotated from the second position to the first position about the longitudinal axis 1120 by the restoring force provided by the biasing member 1196. The movement of the plunger engagement sleeve 1114 and the plunger engagement post 1118 to the first position causes the guide pin 1139 to be guided along the upper surface 1179 within the opening 1162 of the plunger release sleeve 1158 by the restoring force provided by the biasing member 1196.

[0307] 32-35B, an injector assembly 2000 according to another embodiment of the present disclosure is shown. The injector assembly 2000 includes a housing 2002 that houses an automatic or powered fluid injector. The fluid injector is configured to interface with and operate one or more syringes, each of which may be independently filled with a medical fluid, such as contrast media, saline, or any desired medical fluid, as similarly described above with respect to FIG. 1 or FIG. 3. For example, the injector housing 2002 is configured to hold syringes 2006a, 2006b, each housing a medical fluid.

[0308] As known in the art, the syringes 2006a, 2006b are often made of polypropylene or similar material with a certain minimum wall thickness. During certain procedures, such as angiography procedures, the syringes 2006a, 2006b may be subjected to pressures of up to 1200 psi when used to inject fluids into a patient, and thus the thickness and resiliency of the syringes is important in ensuring that the syringes do not radially expand, burst, disengage from the injector, or leak. To further combat possible radial expansion of the syringes 2006a, 2006b when subjected to high pressure injections, respective pressure jackets 2004a, 2004b may be utilized to contain and retain the syringes 2006a, 2006b. The pressure jackets 2004a, 2004b act to limit the radial expansion of the syringe barrels. That is, during an injection procedure, the outer walls of the syringes 2006a, 2006b expand against the inner walls of their respective pressure jackets 2004a, 2004b, thereby limiting radial expansion of the outer walls of the syringes that could otherwise lead to rupture or leakage.

[0309] The pressure jackets 2004a, 2004b may be separate elements or may be formed in a one-piece integral design. The pressure jackets 2004a, 2004b are held on the injector head of the housing 2002 via respective mounting interfaces 2010a, 2010b. Suitable non-limiting examples of pressure jackets including syringe retaining features for use in CV injection procedures are described in International Application Publication No. US2020 / 049885, which is incorporated herein by reference.

[0310] In addition to the radial forces acting on the syringes 2006a, 2006b and pressure jackets 2004a, 2004b, the elastic properties of the structural components that constrain the syringes 2006a, 2006b also allow for significant axial movement during high pressure injection. For example, 1.6 in at 1200 psi. 2A single 150 ml syringe having a cross-sectional area of ​​150 mm may require a force of 2400 psi to restrain the forward movement of the syringe. To limit this axial movement of the syringes 2006a, 2006b, respective caps 2008a, 2008b may be used to partially enclose the distal ends of the syringes 2006a, 2006b and retain the syringes 2006a, 2006b within the injector and pressure jackets 2004a, 2004b during high pressure injection. The caps 2008a, 2008b may have openings formed at their distal ends to allow at least a portion of the necks 2009a, 2009b of the syringes 2006a, 2006b to protrude therethrough, thereby allowing the syringes 2006a, 2006b to be connected to a fluid line leading to a patient.

[0311] Due to the axial forces imposed on the syringes 2006a, 2006b, it is desirable that the attachment interfaces between the pressure jackets 2004a, 2004b and the housing 2002, and / or between the caps 2008a, 2008b and the pressure jackets 2004a, 2004b, are strong enough to resist reversal of axial movement or unintentional separation. However, while strength is important, it is also important that an operator be able to easily remove the caps 2008a, 2008b and / or the pressure jackets 2004a, 2004b, as is necessary to remove or insert the syringes 2006a, 2006b. It is therefore desirable that the connection interfaces between the pressure jackets 2004a, 2004b and the housing 2002 be sufficiently secure while allowing for easy attachment and removal. Similarly, it is desirable that the connection interfaces between the caps 2008a, 2008b and the pressure jackets 2004a, 2004b, are also secure while allowing for easy attachment and removal.

[0312] To achieve these desirable properties, the mounting interfaces 2010a, 2010b of the pressure jackets 2004a, 2004b can have connector features similar to those of the plunger 326 illustrated and described with reference to Figures 6-8C, while the mounting interfaces 2020a, 2020b of the housing 2002 shown in Figure 32 can have connector features similar to those of the various embodiments of the plunger engagement mechanism illustrated and described with reference to Figures 9-31D. That is, the mounting interfaces 2010a, 2010b can include one or more resiliently flexible retaining members having catches, similar to the resiliently flexible retaining member 368 and catch 374 illustrated and described with reference to Figures 6-8C, disposed circumferentially around the opening at the proximal end of the pressure jackets 2004a, 2004b. Similarly, the mounting interfaces 2020a, 2020b of the housing 2002 can include one or more features similar to the plunger-engaging sleeves and plunger-engaging posts shown and described with reference to Figures 9-31D.

[0313] In operation, the mounting interfaces 2010a, 2010b and 2020a, 2020b are configured to interact in a manner substantially similar to the interaction between the plunger 326 and the plunger engagement mechanism illustrated and described in detail with reference to Figures 9-31D. That is, the mounting interfaces 2010a, 2010b are axially oriented toward the respective mounting interfaces 2020a, 2020b such that the respective mounting interfaces 2010a, 2010b and the mounting interfaces 2020a, 2020b interact to allow the pressure jackets 2004a, 2004b to be secured to the housing 2002. One or more retaining members within the mounting interfaces 2020a, 2020b, which in certain embodiments can protrude from a distal end of the mounting interfaces 2020a, 2020b, are then configured to engage with a lip of an engagement ring in each of the mounting interfaces 2010a, 2010b to securely attach the pressure jackets 2004a, 2004b to the housing 2002.

[0314] To separate the pressure jackets 2004a, 2004b from the housing 2002, the pressure jackets 2004a, 2004b can be rotated (together or separately) relative to the housing 2002. Rotation of the pressure jackets 2004a, 2004b allows the mounting interfaces 2010a, 2010b to interact with the mounting interfaces 2020a, 2020b in a manner similar to that described above with reference to FIGS. 9-31D. This motion interaction pushes the at least one retaining member radially outward or inward such that the at least one retaining member disengages from corresponding structure on the mounting interfaces 2010a, 2010b, at which point the pressure jackets 2004a, 2004b can be axially separated from the housing 2002.

[0315] Alternatively, upon insertion, the proximal end of the body of the syringe 2006a, 2006b within the pressure jacket 2004a, 2004b may act similar to a plunger engagement post to lock a catch on a corresponding flexible retaining member of the pressure jacket into a corresponding locking groove or lip in the pressure jacket port of the injector. Removal of the syringe 2006a, 2006b from the pressure jacket 2004a, 2004b, for example after completion of an injection protocol, may disengage the flexible retaining member of the pressure jacket from the corresponding locking groove or lip in the pressure jacket port, allowing removal of the pressure jacket from the port.

[0316] According to an alternative aspect of the present disclosure, the structural details of the mounting interfaces 2010a, 2010b and 2020a, 2020b described above can be reversed, i.e., the mounting interfaces 2010a, 2010b of the pressure jackets 2004a, 2004b can include, for example, at least one retaining member and corresponding features, while the mounting interfaces 2020a, 2020b can include features of a plunger engagement mechanism as described herein with reference to Figures 9-31D.

[0317] 34, 35A, and 35B, an alternative embodiment of the present disclosure is shown. As described above with respect to FIGS. 32-33, caps 2008a, 2008b may be provided generally about the distal end of each pressure jacket 2004a, 2004b to axially retain the respective syringe. As shown in FIG. 35A, cap 2008 may have a mounting interface 2014 for mounting to the pressure jacket, as well as an opening 2016 formed therein to allow a portion of the distal end of the syringe to extend therethrough.

[0318] To obtain a secure connection between the pressure jackets 2004a, 2004b and the caps 2008a, 2008b, it may be advantageous to configure the respective interfaces between the pressure jackets 2004a, 2004b and the caps 2008a, 2008b to interact in a manner substantially similar to the interaction between the various embodiments of the plunger 326 and the various embodiments of the plunger engagement mechanism shown and described in detail in Figures 9-31D. As shown in Figure 33, the pressure jackets 2004a, 2004b can have respective attachment interfaces 2012a, 2012b at their distal ends for engagement with the respective caps 2008a, 2008b. The attachment interfaces 2012a, 2012b can include one or more plunger engagement mechanisms as shown and described with respect to Figures 9-31D. Similarly, the mounting interface 2014 of the cap 2008 shown in FIG. 35A may include one or more resiliently deflectable retention members 368 with corresponding catches 374 as shown and described with reference to FIGs. 6-8C. The engagement between the mounting interfaces 2012a, 2012b of the pressure jackets 2004a, 2004b and the mounting interfaces 2014 of the respective caps 2008 may be the same or substantially similar to the engagement between the plunger 326 and the plunger engagement mechanism described above with respect to FIGs. 9-31D. In this manner, the caps 2008a, 2008b may be securely engageable with and easily removable from the distal ends of the pressure jackets 2004a, 2004b.

[0319] As an alternative to the cap 2008 being separate from and surrounding a portion of the syringe, FIG. 35B illustrates a syringe assembly 2030 having a syringe body 2032 with an integral cap 2036. That is, the cap 2036 may be molded or formed directly with the syringe body 2032. A neck portion 2034 extends from a distal face of the cap 2036 to provide a connection point for a fluid line leading to a patient. A mounting interface 2038, similar to the mounting interface 2014 shown and described with respect to FIG. 35A, is formed in the cap 2036. As also described above with respect to FIGS. 32 and 35A, the mounting interface 2038 can include a feature that interacts with one of the corresponding mounting interfaces 2012a, 2012a of the pressure jackets 2004a, 2004b. Again, the engagement between the mounting interfaces 2012a, 2012b of the pressure jackets 2004a, 2004b and the mounting interfaces 2038 of the respective syringe assemblies 2030 may be the same or substantially similar to that described above with respect to Figures 9-31D.

[0320] According to an alternative embodiment of the present disclosure, the structural details of the mounting interfaces 2012a, 2012b, and 2014 described above can be reversed. That is, the mounting interfaces 2012a, 2012b of the pressure jackets 2004a, 2004b can include, for example, at least one retaining member and corresponding features, while the mounting interface 2014 of each cap 2008 can include corresponding features associated with the plunger engagement mechanism described herein with reference to Figures 9-31D. Similarly, the structural details of the mounting interfaces 2012a, 2012b, and 2038 described above can be reversed.

[0321] While shown and described as being integral with pressure jackets 2004a, 2004b, one or both of mounting interfaces 2010a, 2010b and 2012a, 2012b of pressure jackets 2004a, 2004b may alternatively be formed of separate components mountable to the proximal or distal ends of pressure jackets 2004a, 2004b. In this manner, a conventional pressure jacket can be adapted with one or more separate mounting interfaces to enable the pressure jacket to reliably interface with a syringe assembly having an appropriately equipped housing, cap similar to cap 2008, and / or integral cap, similar to syringe assembly 2030 described above.

[0322] Although the present disclosure has been described in detail for purposes of illustration based on what are presently considered to be the most practical and preferred embodiments, it should be understood that such detail is for that purpose only, and that the present disclosure is not limited to the disclosed embodiments, but rather is intended to cover modifications and equivalent arrangements. For example, it should be understood that the present disclosure contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment. [Explanation of symbols]

[0323] 10 Fluid Injector System 11 User Interface 12, 300, 2006a, 2006b Syringe 13, 400, 500, 600, 700, 800, 900, 1000, 1100, 2700 Piston 14 Injector housing 15 Pressure Jacket 16 Syringe port 17 Fluid Path Set 17A First Fluid Path, Bulk Fluid Path 17B Second Fluid Path, Bulk Fluid Path 18 Syringe Barrel 19A, 19B Bulk fluid containers 20, 320, 336, 382, ​​432, 470, 474, 490, 532, 632, 674, 713, 813, 1074, 1113, 1132, 1153, 1176 Proximal end 21A, 21B Bulk fluid path 23A, 23B Bulk Fluid Valves 26, 326 Plunger 100 Dual Syringe Angiography Injector System, Injector 200 Controller 202 Bus 204 Processor 206 Memory 208 Memory Components 210 Input Components 212 Output Components 214 Communication Interface 240 Upstream Air Detector 250 Air Detector Tube Area 315 Syringe Longitudinal Axis 318 Syringe Barrel 319 Side wall 321, 360, 442, 1042, 1142 outer surface 322 Nozzle 323, 352, 428, 436, 728, 828, 1128 inner surface 324, 338, 426, 468, 476, 478, 486, 626, 676, 726, 815, 826, 1076, 1117, 1147, 1151, 1174 Distal end 325 Internal volume 327 Driving Shoulder 329, 444, 544, 644, 1044, 1144 Toothed part 330 Insert Section 331 Syringe holding member 332 Plunger body 334 Plunger Longitudinal Axis 335 Drip flange 339 Circumferential side wall 340 Internal cavity 342 Cone-shaped part 344 Cylindrical part 345, 456, 679, 1156 Ledge 346 End 347a, 673 First part 347b, 675 second part 348 Molded boss, surface 350 Retaining Rib 356 Extension part 357 Plunger cover 358 Elastic Seal 362 Circumferential groove 364 External Surfaces 368 Flexible holding member 366 Sealing Elements 369, 369b Rounded or inclined release surface 370 first end, first distal end 372 second end, second proximal end 374 Catch 377 Distal surface 375 Rounded or beveled catch surface 379, 2799 proximal surface 380, 390 Release tab 384 Guide Surface 402 Electric motors, drive mechanisms 404, 704, 804, 1104 main unit 406, 606, 706, 806, 920, 1006, 1106 Piston Head 412 Piston engagement sleeve, plunger engagement mechanism, piston engagement mechanism 414 Piston engagement sleeve, plunger engagement sleeve 415, 515, 615, 815, 1015, 1115 Receptive space 416, 516, 616, 716, 816, 1016, 1116 central opening 418 Plunger Engagement Post 420 Longitudinal piston axis, longitudinal axis 422, 822, 1122 Actuators 424 Actuator, hollow body 430, 530, 630, 730, 1130 Slope section 434, 634, 834 Locking rib 438, 538 Longitudinal groove 439, 539, 1139 Guide pin 440, 540 Distal Stop 446, 1146, 2002 Housing 448 Connection parts 450 Male Thread Connector 452, 519 Proximal part 454 Distal part 458, 558, 1158 Plunger Release Sleeve 460, 560, 1160 Cylindrical sidewall 462, 523, 562, 1162, 2016 Openings 463, 563, 1163 Longitudinal surface 464 Longitudinal axis, inclined surface 466, 566, 1166 sloped surface 472 Shaft, Light 474, 1175 Printed Circuit Boards 478, 678, 1078 Tapered end face 480, 1119, 1180 Seal 482, 531, 564 Longitudinal axis 484, 2784 Elastic elastic members 488 Ledge 496, 1196 Pressing member 512, 612, 712, 812, 1012 Plunger engagement mechanism 514, 714, 814, 2714 Plunger Engagement Sleeve 518 Plunger engagement post, piston engagement post 520 piston longitudinal axis, longitudinal piston axis, longitudinal axis 521, 721 Post part 524, 624, 724, 824, 1024, 1124 hollow body 525 Connection piece 526 Distal end, end 527, 1127 Locking groove 528 Inner surface 533 Through hole 614 Piston engagement sleeve, plunger engagement sleeve 618, 718, 818, 1018 Plunger Engagement Post 620 Longitudinal piston axis, longitudinal axis 665 Groove 667 Longitudinal axis, outer surface 671, 1071 Rotation mechanism 672, 1072, 1172 Shaft 705, 805, 1105 Detection members 707, 1107 pin 709, 809, 1109 Sensors 711 Spring 715 Distal end, receptive space 717 First Section 719 Second step 720 Longitudinal axis, longitudinal piston axis 722 Actuator 723 Proximal part 729, 950 Locking lip 737 Radial Groove 803, 1173 Light 807 Detection Sleeve 817 Spring 820 Longitudinal piston axis, longitudinal axis 901 Stem 912 Plunger engagement mechanism, piston engagement mechanism 940 Piston Cavity 960 Rounded or beveled distal surface 970 Rounded or beveled proximal surface 980 Locking member 990 Recess 1014 Plunger engagement sleeve, piston engagement sleeve 1020 Longitudinal piston axis 1065 Locking groove 1112 Plunger engagement sleeve, plunger engagement mechanism, piston engagement mechanism 1114 Plunger engagement sleeve, piston engagement sleeve 1118 Plunger engagement post, plunger engagement sleeve, piston engagement post 1120 Longitudinal piston axis, longitudinal axis 1126 Distal end, end 1145 Plunger release tooth 1149 Point 1152 Proximal part 1154 Distal part 1161 Inner cavity 1164 Longitudinal axis, inclined surface 1178 Tapered end face, tapered surface 2000 Injector Assembly 2004a, 2004b Pressure Jacket 2008, 2008a, 2008b, 2036 Cap 2009a, 2009b Neck 2010a, 2010b, 2012a, 2012b, 2014, 2020a, 2020b, 2038 Mounting Interface 2030 Syringe Assembly 2032 Syringe body 2034 Neck part 2750 Flexible retaining member 2755 Retaining catch 2774 Engagement flange or catch 2798 Movable locking member

Claims

1. 1. A plunger for use with a syringe, said plunger comprising: a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting said proximal end and said distal end; at least one retention member associated with the plunger body and extending proximally therefrom, the at least one retention member comprising: a first end connected to the plunger body; a second end proximal to the first end and resiliently deflectable radially relative to the first end; at least one catch at the second end; At least one retaining member comprising: Equipped with The at least one retaining member may have an outer surface configured to engage a plunger engagement sleeve of a plunger engagement mechanism on a piston of a fluid injector system when the plunger is in a locked condition with the piston; the at least one retaining member having an inner surface configured to engage a plunger engagement post of the plunger engagement mechanism when the plunger is in a locked condition with the piston; the at least one catch is configured to fixedly engage a locking feature of one of the plunger engagement sleeve and the plunger engagement post when the plunger is in a locked condition with the piston to prevent axial movement of the plunger relative to the piston; the at least one catch having a first rounded or beveled proximal surface at a proximal end of the at least one catch for fixedly engaging with a distal end of the locking feature of one of the plunger engagement sleeve and plunger engagement post during engagement of the plunger on the piston, and a second rounded or beveled distal surface at a distal end of the at least one catch for fixedly engaging with a proximal end of the locking feature of one of the plunger engagement sleeve and plunger engagement post during disengagement of the plunger from the piston; A plunger, wherein in an unlocked state of the plunger, the first rounded or beveled proximal surface and the second rounded or beveled distal surface of the at least one catch are configured to radially deflect the second end of the at least one retaining member upon axial movement of the piston relative to the plunger due to bending interaction of the at least one catch with the locking feature of one of the plunger engagement sleeve and the plunger engagement post.

2. The plunger of claim 1 , wherein the at least one retention member comprises a plurality of retention members spaced about the central longitudinal axis.

3. The plunger of claim 1 , wherein the at least one retention member extends proximally in a direction parallel to the central longitudinal axis.

4. The plunger of claim 1 , wherein the plunger is configured to engage with the plunger engagement mechanism regardless of an angular orientation of the plunger relative to the piston of the fluid injector system.

5. The plunger of claim 1 , wherein the at least one catch projects radially inward from the inner surface of the at least one retaining member in a direction toward the central longitudinal axis.

6. The plunger of claim 1 , wherein the at least one catch projects radially outward from the outer surface of the at least one retaining member in a direction away from the central longitudinal axis.

7. The plunger of claim 1 , wherein the at least one catch defines a locking recess for receiving at least a portion of the plunger engagement feature when the plunger is connected to the piston.

8. The plunger of claim 1, wherein the at least one catch protrudes 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 catch is configured to be received within the locking feature, which may be shaped as a locking groove protruding radially inward from the outer surface of the plunger engagement post, when the plunger is in an engaged state with the piston.

9. The plunger of claim 1 , wherein the plunger body has a conical portion at the distal end and a cylindrical portion at the proximal end.

10. The plunger of claim 9 , wherein the at least one retention member projects proximally from an inner surface of the cone-shaped portion.

11. 11. The plunger of claim 10, further comprising a plurality of release tabs projecting radially inward or proximally from an inner surface of the cylindrical portion, each of the plurality of release tabs configured to interact with the plunger engagement sleeve to actuate release of the plunger from the piston upon rotation of the plunger about the central longitudinal axis.

12. The plunger of claim 11 , wherein a proximal end of each of the plurality of release tabs has a pointed guide surface.

13. 2. The plunger of claim 1, wherein when the plunger is in an engaged state with the piston, the at least one catch protrudes radially outward from an outer surface of the at least one retaining member in a direction away from the central longitudinal axis, and the at least one catch is configured to be received within a locking feature shaped as a locking groove protruding radially inward from an inner surface of the plunger engaging sleeve.

Images