System and method for syringe plunger engagement with injector

Abstract

To provide a plunger for use with a syringe.SOLUTION: The plunger includes a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal and distal ends. The plunger further includes at least one retaining member associated with and extending proximally from the plunger body. The at least one retaining member has a first end connected to the plunger body, a second end proximal to the first end and radially and resiliently deflectable relative to the first end, and at least one catch on the second end. A fluid injector system includes a piston having a plunger engagement mechanism configured for interacting with the at least one retaining element of the plunger to releasably engage the plunger for reciprocally driving the plunger within a barrel of the syringe.SELECTED DRAWING: Figure 23A

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 62 / 705,265, filed on Jun. 18, 2020, the disclosure of which is hereby incorporated by reference in its entirety.

[0002] The present disclosure generally relates to a system including a front - loading syringe and / or a 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 with respect to the piston of the fluid injector.

Background Art

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

[0004] Typically, a fluid injector has at least one drive member, such as a piston, that connects to a syringe, for example, via a connection to an engagement feature of the proximal end wall of the syringe. The syringe can 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 direction and / or a distal direction with respect to the longitudinal axis of the barrel to draw fluid into or deliver fluid from the syringe barrel.

[0005] To facilitate the engagement of a syringe plunger with a piston of a fluid injector, various connection interfaces have been developed. In some embodiments, a syringe having a retention feature is inserted into a syringe port of a fluid injector by aligning the syringe with a corresponding locking feature provided on the fluid injector. Such alignment also aligns a plunger within the syringe with a piston on the fluid injector so that the piston can engage the plunger and reciprocally drive the plunger within the syringe barrel to draw fluid into the syringe barrel or deliver fluid between 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 extensible pin that engages a lip on the plunger.

[0006] Many of the existing connection interfaces have a structure that requires a complex piston head having various sensor elements and active engagement structures. There is a need in the art for an improved connection interface that enables 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 a syringe with a 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, 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 respect to a piston of a fluid injector, continues to be sought.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

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Patent Document 4

Patent Document 5

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Patent Document 7

Patent Document 8

Patent Document 9

Summary of the Invention

Means for Solving the Problems

[0008] In this technical field, there is a need for an improved connection interface between a syringe plunger and a piston of a fluid injector that overcomes the drawbacks of the prior art. There is an additional need for a method of engaging and disengaging a syringe plunger with respect to a piston of a fluid injector to enable rapid loading or removal of a syringe with respect to the fluid injector.

[0009] According to some embodiments, a plunger for use with a 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 end and the distal end, and at least one retaining member associated with the plunger body and extending proximally therefrom, the at least one retaining member including a first end connected to the plunger body, a second end proximal to the first end and radially elastically deflectable relative to the first end, and at least one catch of the second end. The at least one retaining 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 state with the piston. The at least one retaining member can have an inner surface configured to engage a plunger engagement post of the plunger engagement mechanism when the plunger can be in a locked state with the piston. The at least one catch can be configured to engage one of the locking functional portions of the plunger engagement sleeve and the plunger engagement post when the plunger can be in a locked state with the piston to prevent axial movement of the plunger relative to the piston. The at least one catch can be configured to radially deflect the second end of the at least one retaining member during axial movement of the piston relative to the plunger in an unlocked state of the plunger from the piston by engagement of the at least one catch with one of the locking functional portions of the plunger engagement sleeve and the plunger engagement post.

[0010] According to some embodiments, at least one retaining member can include a plurality of retaining members spaced apart about a central longitudinal axis. The plurality of retaining members may be equally spaced apart about the central longitudinal axis. At least one retaining member may extend proximally in a direction parallel to the central longitudinal axis or in a direction inclined with respect to the central longitudinal axis. At least one retaining member may be continuously linear or curved between a first end and a second end. The plunger may be configured to engage a plunger engagement mechanism regardless of the angular orientation of the plunger relative to the piston of the fluid injector.

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

[0012] According to some embodiments, at least one catch can project radially inwards from the inner surface of at least one retaining member in a direction towards the central longitudinal axis or radially outwards from the outer surface of at least one retaining member in a direction away from the central longitudinal axis. 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. At least one catch may project radially inwards from the inner surface of at least one retaining member in a direction towards the central longitudinal axis, and at least one catch may be configured to be received within a locking functional portion that can be formed as a locking groove projecting radially inwards from the 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 the distal end and a cylindrical portion at the proximal end. At least one retaining member may project proximally from the inner surface of the conical portion. The plurality of release tabs may project radially inwards from the inner surface of the cylindrical portion or project proximally from the inner surface of the cylindrical portion, and each of the plurality of release tabs is configured to interact with a plunger engagement sleeve to cause release of the plunger from the piston upon rotation of the plunger about the central longitudinal axis. The proximal end of each of the plurality of release tabs can 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 provided around at least a portion of the circumferential side wall 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, a fluid injector system may include at least one reciprocable 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 reciprocally drive the plunger within the syringe by movement of the at least one piston. The plunger engagement mechanism may include a plunger engagement sleeve having a hollow body, a plunger engagement post receivable within the hollow body of the plunger engagement sleeve, and an actuator operably connected to one of the plunger engagement sleeve and the plunger engagement post and configured to move one of the plunger engagement sleeve and the plunger engagement post between an engaged position and a disengaged position. In the engaged position, the plunger engagement post may be disposed within the hollow body of the plunger engagement sleeve to capture at least one elastic flexible retaining 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 of the hollow body of the plunger engagement sleeve to permit flexible insertion or removal of at least one elastic 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 the engaged position and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement post to the disengaged position. The actuator may automatically move to the disengaged state during a power loss to the actuator. The actuator may be capable of becoming engaged only during a proximal movement of the at least one piston. At least one biasing element may be provided for moving the actuator from the engaged state to the disengaged state.

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

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

[0020] According to some embodiments, at least one sensor may be 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. The plunger detection sensor may be configured to detect the presence of at least one retaining member of the plunger in a 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 the direction from the distal end of the plunger engagement sleeve to the proximal end of the plunger engagement sleeve. The plunger engagement post can include a locking groove that projects radially inwardly from the outer surface of the plunger engagement post, and the locking groove can be configured to receive at least one catch on at least one retaining member of the plunger. 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 can be moved to a disengaged position. The plunger engagement post may have a body with a stepped outer diameter that decreases in the 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 can include a locking feature that projects radially inwardly from the inner surface of the plunger engagement collar. The locking feature can be configured to engage 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 can be moved to an engaged position. 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 can be moved to a disengaged position.

[0023] According to some embodiments, the fluid injector system can further include a syringe having a barrel with a proximal barrel end, a distal barrel end having a discharge nozzle, and a barrel sidewall extending between the proximal barrel end and the distal barrel end, and a plunger slidably disposed within the barrel and reciprocally movable between the proximal barrel end and the distal barrel 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 end and the distal end, and at least one retaining member associated with the plunger body and extending proximally therefrom.

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

[0026] According to some embodiments, the plunger can be configured to engage a plunger engagement mechanism regardless of the angular orientation of the plunger relative to the piston of the fluid injector. The at least one catch can project radially inwardly from the inner surface of the at least one retaining member in a direction towards the central longitudinal axis. The at least one catch can be configured to be received within a locking functional portion that can be shaped as a locking groove projecting radially inwardly from the outer surface of the plunger engagement post when the plunger can be in a locked state with the piston.

[0027] According to some embodiments, at least one catch can project radially inwards from the inner surface of at least one retaining member in a direction towards the central longitudinal axis. According to some embodiments, at least one catch can project radially outwards from the outer surface of 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 the distal end and a cylindrical portion at the proximal end. At least one retaining member may project proximally from the inner surface of the conical portion. A plurality of release tabs may project radially inwards from the inner surface of the cylindrical portion, and each of the plurality of release tabs is configured to interact with a plunger engagement sleeve to cause release of the plunger from the piston upon rotation of the plunger about the central longitudinal axis. The proximal end of each of the plurality of release tabs can have a pointed guide surface.

[0029] According to some embodiments, a fluid injector system can include a plunger engagement mechanism that includes at least one reciprocable piston having a piston head and a plunger of a syringe connected to the fluid injector system for reciprocally driving a plunger within the syringe by movement of the at least one piston, the plunger engagement mechanism being configured to engage with the piston head, the plunger engagement mechanism including a plunger engagement sleeve having a hollow body with a longitudinal axis and a plunger engagement post receivable within 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.

[0030] According to some embodiments, the plunger engagement post may be axially movable from the proximal end of the piston towards the distal end of the piston. The plunger release sleeve may include a plurality of plunger release teeth that project radially outward from the 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 may surround at least a portion of the plunger engagement sleeve, and the plunger release sleeve may be configured to rotate about the longitudinal axis along with the rotation of the plunger engagement sleeve. The plunger release sleeve may include an opening having an inclined surface that may be inclined with respect to the direction of the longitudinal axis in a direction from the distal end of the plunger release sleeve towards the proximal end of the plunger release sleeve.

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

[0034] According to some embodiments, the actuator is operably connected to a 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 the hollow body of the plunger engagement sleeve and configured to capture at least one elastic flexible retaining member associated with the plunger within the 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 allow for the flexible insertion or removal of at least one elastic flexible retaining 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 can have an engaged state for moving one of the plunger engagement sleeve and the plunger engagement post to the engaged position and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement post to the disengaged position. The actuator may automatically move to the disengaged state during a power loss to the actuator. The actuator can be in the engaged state only during the proximal movement of at least one piston.

[0036] According to some embodiments, at least one biasing element is configured to move the actuator from the engaged state to the disengaged state. The rotational or linear movement 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 the operation of the actuator.

[0037] According to some embodiments, at least one sensor may be configured to detect the 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 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.

[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 can include a locking groove that projects radially inwardly from the outer surface of the plunger engagement post, and the locking groove can be configured to receive at least one catch on at least one retaining member of the plunger. 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 can be moved to the disengaged position.

[0039] According to some embodiments, the fluid injector system can further include a syringe having a barrel with a proximal end of the barrel, a distal end of the barrel having a discharge nozzle, and a barrel sidewall extending between the proximal end of the barrel and the distal end of the barrel, and a plunger slidably disposed within the barrel and reciprocally movable between the proximal end of the barrel and the distal end of the barrel.

[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 end and the distal end, and at least one retaining member associated with the plunger body and extending proximally therefrom.

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

[0042] According to some embodiments, the plunger may be configured to engage a plunger engagement mechanism 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 project radially inwards from the inner surface of the at least one retaining member in a direction towards the central longitudinal axis. The at least one catch may be configured to be received within a locking functional part that can be shaped as a locking groove projecting radially inwards from the outer surface of the plunger engagement post when the plunger can be in a locked state with the piston.

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

[0045] According to some embodiments, the plunger body may have a conical portion at the distal end and a cylindrical portion at the proximal end. At least one retaining member may project proximally from the inner surface of the conical portion. The plurality of release tabs may project radially inwards from the inner surface of the cylindrical portion, or project proximally from the inner surface of the cylindrical portion, and each of the plurality of release tabs is 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. The 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 set forth in the clauses numbered below.

[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 end and the distal end; and at least one retaining member associated with the plunger body and extending proximally therefrom, the at least one retaining member comprising: a first end connected to the plunger body; a second end proximal to the first end and radially elastically deflectable relative to the first end; and at least one catch at the second end. The at least one retaining 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 is in a locked state with the piston. The at least one retaining member has an inner surface configured to engage a plunger engagement post of the plunger engagement mechanism when the plunger is in a locked state with the piston. The at least one catch is configured to engage one of a locking feature of the plunger engagement sleeve and the plunger engagement post when the plunger is in a locked state with the piston to prevent axial movement of the plunger relative to the piston. The at least one catch is configured to radially deflect the second end of the at least one retaining member during axial movement of the piston relative to the plunger in an unlocked state of the plunger from the piston by engagement of the at least one catch with one of a locking feature of the plunger engagement sleeve and the plunger engagement post.

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

[0049] Clause 3. The plunger according to clause 2, wherein the plurality of retaining members are equally spaced apart around the central longitudinal axis.

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

[0051] Clause 5. The at least one retaining member is the plunger according to any one of Clauses 1 to 3, extending proximally in a direction inclined with respect to the longitudinal axis.

[0052] Clause 6. The at least one retaining member is the plunger according to any one of Clauses 1 to 5, being linearly continuous between the first end and the second end.

[0053] Clause 7. The at least one retaining member is the plunger according to any one of Clauses 1 to 5, being curvilinearly continuous between the first end and the second end.

[0054] Clause 8. The plunger is configured to engage with a plunger engagement mechanism regardless of the angular orientation of the plunger with respect to the piston of the fluid injector, the plunger according to any one of Clauses 1 to 7.

[0055] Clause 9. The at least one catch has a first surface at the proximal end of the at least one catch configured to engage with the distal end of one of the locking functional portions of the plunger engagement sleeve and the plunger engagement post during engagement of the plunger with the piston, and a second surface at the distal end of the at least one catch configured to engage with the proximal end of one of the locking functional portions of the plunger engagement sleeve and the plunger engagement post during disengagement of the plunger from the piston, the plunger according to any one of Clauses 1 to 8.

[0056] Clause 10. The at least one catch projects radially inwards from the inner surface of the at least one retaining member in a direction towards the central longitudinal axis, the plunger according to any one of Clauses 1 to 9.

[0057] Clause 11. The at least one catch projects radially outwards from the outer surface of the at least one retaining member in a direction away from the central longitudinal axis, the plunger according to any one of Clauses 1 to 10.

[0058] Clause 12. The plunger according to any one of Clauses 1 to 11, wherein at least one catch defines a locking recess for receiving at least a part of the plunger engagement mechanism when the plunger is connected to the piston.

[0059] Clause 13. The plunger according to any one of Clauses 1 to 12, wherein at least one catch projects radially inwards from the inner surface of at least one holding member in a direction towards the central longitudinal axis, and at least one catch is configured to be received within a locking functional part that can be shaped as a locking groove projecting radially inwards from the outer surface of the plunger engagement post when the plunger is in a locked state with the piston.

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

[0061] Clause 15. The plunger according to Clause 14, wherein at least one holding member projects proximally from the inner surface of the conical part.

[0062] Clause 16. The plunger according to Clause 14 or 15, further comprising a plurality of release tabs projecting radially inwards from the inner surface of the cylindrical part or projecting proximally from the inner surface of the cylindrical part, and each of the plurality of release tabs is 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 according to Clause 16, wherein the proximal end of each of the plurality of release tabs has a pointed guide surface.

[0064] Clause 18. The plunger according to any one of Clauses 1 to 17, further comprising a plunger cover that covers at least a part of the distal surface of the plunger body and is provided around at least a part of the circumferential side wall of the plunger body.

[0065] Clause 19. The 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 according to 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 reciprocable piston having a piston head, and a plunger of a syringe associated with the piston head and configured to engage a plunger of the syringe connected to the fluid injector system to reciprocally drive 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, a plunger engagement post receivable within the hollow body of the plunger engagement sleeve, and an actuator operatively connected to one of the plunger engagement sleeve and the plunger engagement post and configured to move one of the plunger engagement sleeve and the plunger engagement post between an engaged position and a disengaged position, wherein in the engaged position, the plunger engagement post is disposed within the hollow body of the plunger engagement sleeve to capture at least one elastic 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 of the hollow body of the plunger engagement sleeve to permit flexible insertion or removal of at least one elastic flexible retaining member of the plunger from the receiving space.

[0068] Clause 22. The fluid injector system according to 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 according to Clause 21, wherein the actuator is manually operated.

[0070] Clause 24. 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, and is the fluid injector system according to any one of Clauses 21 to 23.

[0071] Clause 25. The actuator is the fluid injector system according to any one of Clauses 21 to 24, which is dynamically moved to the disengaged state during a power loss to the actuator.

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

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

[0074] Clause 28. The rotational movement of the actuator moves one of the plunger engagement sleeve and the plunger engagement post proximally or distally in a linear direction, and is the fluid injector system according to any one of Clauses 21 to 27.

[0075] Clause 29. The linear movement of the actuator moves one of the plunger engagement sleeve and the plunger engagement post proximally or distally in a linear direction, and is the fluid injector system according to any one of Clauses 21 to 28.

[0076] Clause 30. The actuator is operably connected to a controller configured to control the operation of the actuator, and is the fluid injector system according to any one of Clauses 21 to 29.

[0077] Clause 31. A fluid injector system according to 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 according to any one of Clauses 21 to 31, wherein the plunger engagement post and the plunger engagement collar are movable linearly or rotationally relative to the piston.

[0079] Clause 33. A fluid injector system according to 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 according to 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 a receiving space between the plunger engagement collar and the plunger engagement post.

[0081] Clause 35. A fluid injector system according to any one of Clauses 21 to 34, wherein the hollow body of the plunger engagement sleeve has 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.

[0082] Clause 36. A fluid injector system according to any one of Clauses 21 to 35, wherein the plunger engagement post includes a locking groove that projects radially inwardly from an outer surface of the plunger engagement post, and the locking groove is configured to receive at least one catch on at least one retaining member of the plunger.

[0083] Clause 37. 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 either the plunger engagement sleeve or the plunger engagement post is moved to the disengaged position. The fluid injector system according to clause 36.

[0084] Clause 38. The plunger engagement post has a body with a stepped outer diameter that decreases in the direction from the distal end of the plunger engagement post to the proximal end of the plunger engagement post. The fluid injector system according to any one of clauses 21 to 37.

[0085] Clause 39. The plunger engagement collar includes a locking feature that projects radially inward from the inner surface of the plunger engagement collar. The locking feature is configured to engage at least one catch on at least one retaining member of the plunger when either the plunger engagement sleeve or the plunger engagement post is moved to the engaged position. The fluid injector system according to any one of clauses 21 to 38.

[0086] Clause 40. 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 either the plunger engagement sleeve or the plunger engagement post is moved to the disengaged position. The fluid injector system according to clause 39.

[0087] Clause 41. A syringe comprising a barrel having a proximal end of the barrel, a distal end of the barrel having a discharge nozzle, and a barrel side wall extending between the proximal end of the barrel and the distal end of the barrel, and a plunger slidably disposed within the barrel and reciprocally movable between the proximal end of the barrel and the distal end of the barrel. The fluid injector system according to any one of clauses 21 to 39.

[0088] Clause 42. The plunger comprises a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal end and the distal end, and at least one retaining member associated with the plunger body and extending proximally therefrom, of the fluid injector system according to Clause 41.

[0089] Clause 43. The at least one retaining member comprises a first end connected to the plunger body, a second end proximal to the first end and radially elastically deflectable relative to the first end, and at least one catch on the second end, the at least one retaining member having an outer surface configured to engage a plunger engagement sleeve when the plunger is engaged with the piston, the at least one retaining member having an inner surface configured to engage a plunger engagement post when the plunger is engaged with the piston, the at least one catch being configured to engage one of a locking feature of the plunger engagement sleeve and the plunger engagement post to prevent axial movement of the plunger relative to the piston when the plunger is engaged with the piston, and the at least one catch being configured to radially deflect the second end of the at least one retaining member during 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, of the fluid injector system according to Clause 41 or 42.

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

[0091] Clause 45. At least one catch projects radially inwards from the inner surface of at least one retaining member in a direction towards the central longitudinal axis, and at least one catch is configured to be received within a locking functional portion shaped as a locking groove that projects radially inwards from the outer surface of the plunger engagement post when the plunger is in a locked state with the piston, of the fluid injector system according to any one of Clauses 41 to 44.

[0092] Clause 46. At least one catch projects radially inwards from the inner surface of at least one retaining member in a direction towards the central longitudinal axis, or at least one catch projects radially outwards from the outer surface of at least one retaining member in a direction away from the central longitudinal axis, of the fluid injector system according to any one of Clauses 41 to 45.

[0093] Clause 47. The plunger body has a conical portion at the distal end and a cylindrical portion at the proximal end, of the fluid injector system according to any one of Clauses 41 to 46.

[0094] Clause 48. At least one retaining member projects proximally from the inner surface of the conical portion, of the fluid injector system according to Clause 47.

[0095] Clause 49. Further comprising a plurality of release tabs projecting radially inwards 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, of the fluid injector system according to Clause 47 or 48.

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

[0097] Clause 51. A fluid injector system, comprising at least one reciprocable piston having a piston head, and a plunger of a syringe connected to the fluid injector system so as to engage with a plunger of the syringe configured to reciprocally drive a 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 with a longitudinal axis, and a plunger engagement post receivable within 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 according to clause 51, wherein the plunger engagement post is axially movable from a proximal end of the piston towards a distal end of the piston.

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

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

[0101] Clause 55. The fluid injector system according to 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 being configured to rotate about the longitudinal axis with rotation of the plunger engagement sleeve.

[0102] Clause 56. The plunger release sleeve comprises an opening having an inclined surface inclined with respect to the direction of the longitudinal axis in a direction from the distal end to the proximal end of the plunger release sleeve, the fluid injector system according to any one of Clauses 51 to 55.

[0103] Clause 57. The plunger engagement post has a guide pin extending in a direction perpendicular to the longitudinal axis, the guide pin being received in the opening of the plunger release sleeve, the fluid injector system according to Clause 56.

[0104] Clause 58. Rotation of the plunger engagement sleeve causes a corresponding rotation of the plunger release sleeve, and the guide pin is guided along the inclined surface from the proximal end to the distal end of the inclined surface, thereby moving the plunger engagement post from the engaged position to the disengaged position, the fluid injector system according to Clause 57.

[0105] Clause 59. The fluid injector system according to 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 biasing member is configured to bias the plunger engagement sleeve to a first position, the fluid injector system according to Clause 59.

[0107] Clause 61. The fluid injector system according to 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. In the engaged position, the plunger engagement post is disposed within the hollow body of the plunger engagement sleeve and is 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. In the disengaged position, the plunger engagement post is disposed at least partially outside of the hollow body of the plunger engagement sleeve to permit flexible insertion or removal of at least one resiliently flexible retaining member of the plunger from the receiving space. The fluid injector system according to clause 61.

[0109] Clause 63. The actuator is a rotary electric motor, a linear electric motor, a linear actuator, or a solenoid. The fluid injector system according to clause 61 or 62.

[0110] Clause 64. The actuator is manually operated. The fluid injector system according to any one of clauses 61 to 63.

[0111] Clause 65. The actuator has an engaged state for moving one of the plunger engagement sleeve and the plunger engagement post to the engaged position and a disengaged state for moving one of the plunger engagement sleeve and the plunger engagement post to the disengaged position. The fluid injector system according to any one of clauses 61 to 63.

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

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

[0114] Clause 68. The fluid injector system according to 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 according to any one of Clauses 61 to 68, wherein the rotational movement of the actuator moves either the plunger engagement sleeve or the plunger engagement post proximally or distally in a linear direction.

[0116] Clause 70. A fluid injector system according to any one of Clauses 61 to 69, wherein the linear movement of the actuator moves either the plunger engagement sleeve or 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 the operation of the actuator.

[0118] Clause 72. A fluid injector system according to any one of Clauses 51 to 71, 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 the engaged position and the disengaged position.

[0119] Clause 73. A fluid injector system according to any one of Clauses 51 to 72, further comprising a plunger detection sensor configured to detect the presence of at least one holding 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 according to any one of Clauses 51 to 73, wherein the hollow body of the plunger engagement sleeve has an opening with a stepped inner diameter that decreases in the direction from the distal end of the plunger engagement sleeve to the proximal end of the plunger engagement sleeve.

[0121] Clause 75. The plunger engagement post includes a locking groove that projects radially inwardly from the outer surface of the plunger engagement post, and the locking groove is configured to receive at least one catch on at least one retaining member of the plunger, the fluid injector system according to any one of Clauses 51 to 74.

[0122] Clause 76. 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 the disengaged position, the fluid injector system according to Clause 75.

[0123] Clause 77. A syringe comprising a barrel having a barrel proximal end, a barrel distal end having a discharge nozzle, and a barrel side wall extending between the barrel proximal end and the barrel distal end, and further comprising a plunger slidably disposed within the barrel and reciprocally movable between the barrel proximal end and the barrel distal end, the fluid injector system according to any one of Clauses 51 to 76.

[0124] Clause 78. The plunger includes a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential side wall connecting the proximal end and the distal end, and at least one retaining member associated with the plunger body and extending proximally therefrom, the fluid injector system according to Clause 77.

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

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

[0127] Clause 81. The at least one catch projects radially inwards from the inner surface of the at least one retaining member in a direction towards the central longitudinal axis. The at least one catch is configured to be received within a locking functional portion that may be shaped as a locking groove projecting radially inwards from the outer surface of the plunger engagement post when the plunger is in a locked state with the piston. The fluid injector system according to any one of clauses 77 to 80.

[0128] Clause 82. The fluid injector system according to any one of Clauses 77 to 81, wherein at least one catch projects radially inwards from the inner surface of at least one holding member in a direction towards the central longitudinal axis, or at least one catch projects radially outwards from the outer surface of at least one holding member in a direction away from the central longitudinal axis.

[0129] Clause 83. The fluid injector system according to any one of Clauses 77 to 82, wherein at least one catch defines a locking recess for receiving at least a part of the plunger engagement mechanism when the plunger is connected to the piston.

[0130] Clause 84. The fluid injector system according to any one of Clauses 77 to 83, wherein the plunger body has a conical portion at the distal end and a cylindrical portion at the proximal end.

[0131] Clause 85. The fluid injector system according to Clause 84, wherein at least one holding member projects proximally from the inner surface of the conical portion.

[0132] Clause 86. The fluid injector system according to Clause 84 or 85, further comprising a plurality of release tabs projecting radially inwards 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 a 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 according to Clause 86, wherein the proximal end of each of the plurality of release tabs has a pointed guide surface.

[0134] A syringe, a syringe plunger, a pressure jacket, and a system having a syringe and / or a syringe plunger, as well as the operating methods and functions of the related elements of the structure and the combination of parts and manufacturing economy, these and other features and characteristics will become more apparent by considering the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, and like reference numerals in the various figures designate corresponding parts. However, it should be clearly understood that the drawings are for illustrative and explanatory purposes only.

Brief Description of the Drawings

[0135]

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[0136] For the purposes of the following description, the terms "upper", "lower", "right", "left", "vertical", "horizontal", "upper part", "bottom", "lateral", "longitudinal", and their derivatives shall relate to the present disclosure as shown in the drawings. Spatial or directional terms such as "left", "right", "inner", "outer", "upper", "lower", etc. should not be considered limiting since the embodiments described herein can 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 to be modified in all instances by the term "about". The terms "approximately", "about", and "substantially" mean within plus or minus 10 percent of the recited value.

[0138] Unless otherwise indicated, all ranges or ratios disclosed herein should be understood to include the starting and ending values, as well as any and all sub-ranges or sub-ratios subsumed therein. For example, a range or ratio described as "1 to 10" includes any and all sub-ranges or sub-ratios between the minimum value 1 and the maximum value 10, i.e., all sub-ranges or sub-ratios starting at a minimum value of 1 or more and ending at a maximum value of 10 or less. The ranges and / or ratios disclosed herein represent the average value over the specified range and / or ratio.

[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 two or more of A, B, and C. For example, "at least A, B, and C" includes one or more of only A, or one or more of only B, or one or more of only 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 one or more of all 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 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", etc. do not refer to a particular order or time series, but are intended to refer to different conditions, characteristics, or elements. All documents referred to in this specification 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 particular devices and processes shown in the accompanying drawings and described in the following specification are merely exemplary embodiments of the present disclosure. Accordingly, the specific dimensions and other physical characteristics relating to the examples disclosed herein should not be considered limiting.

[0142] As used herein, the terms "parallel" or "substantially parallel" mean a relative angle between two objects, such as elongate objects, including the recited values, from 0° to 5°, or from 0° to 3°, or from 0° to 2°, or from 0° to 1°, or from 0° to 0.5°, or from 0° to 0.25°, or from 0° to 0.1° (when extended to their theoretical intersection).

[0143] As used herein, the terms "perpendicular" or "substantially perpendicular" 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°, including the recited values.

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

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

[0146] The systems and devices described herein refer to computer tomography (CT) contrast agent injection systems, angiography (CV) contrast agent injection systems, positron emission tomography (PET) contrast agent injection systems, and magnetic resonance imaging (MRI) contrast agent injection systems, although other pressurized injection protocols can also incorporate the various embodiments described herein for securing a syringe plunger to the piston of a fluid injector.

[0147] With reference to the drawings, in which like reference numerals refer to like parts throughout several views, the present disclosure generally relates to a syringe plunger and a connection interface for connecting the syringe plunger to a piston of a fluid injector. Various embodiments are directed to a syringe plunger that can be connected to and disconnected from a piston. In various embodiments, such a piston can be actuated manually, mechanically, hydraulically, or electrically. Further, the present disclosure provides a quick and easy solution for engaging and / or disconnecting a syringe plunger from a piston without involving a specific rotational orientation or alignment of the plunger relative to the piston. For example, the piston may be advanced forward until it engages 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 can be attached to the plunger, for example, a simple rotation of the plunger due to rotation of the syringe about its longitudinal axis relative to the piston may cause separation of the two elements. In another embodiment, the engagement and disengagement of the piston with respect to the plunger may be initiated automatically as part of a programmed injection protocol, such as during the start and completion of a fluid injection protocol, or by a user, for example, by user input to a fluid injector controller, and may be executed by the fluid injector controller. In further embodiments or aspects, the present disclosure also generally relates to a pressure jacket and a cap for the pressure jacket, and the same connection interface for connecting a syringe plunger to a piston of a fluid injector can be used to connect the pressure jacket to the fluid injector and / or to connect the cap of the pressure jacket to the pressure jacket itself.

[0148] Referring to FIG. 1, a non-limiting example of a fluid injector system 10, such as an automatic or powered fluid injector (hereinafter referred to as "injector 10"), is adapted to interact with and operate at least one syringe 12 and a corresponding plunger 26, each of which may be independently filled with a medical fluid F, such as a contrast medium, saline, or any desired medical fluid. The injector 10 can 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, and several syringes 12 may be arranged side by side or in other relationships, and may include plungers 26 that are operated separately by respective pistons 13 associated with the injector 10. In an embodiment where two syringes are arranged side by side and filled with two different medical fluids, the injector 10 can deliver fluid from one or both of the syringes 12.

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

[0150] At least one fluid path set 17 can be fluidly connected to at least one syringe 12 to deliver a 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. The fluid flow from the at least one syringe 12 can be adjusted by a controller 200 (FIG. 2). The controller 200 can operate various pistons, piston mechanical components (such as components for engaging and disengaging the piston with the plunger), valves, and / or flow adjustment structures to adjust the delivery of medical fluids, such as saline and contrast agents, to the patient based on the injection parameters selected by the user. One aspect of a suitable front-loading fluid injector that can be modified for use with the above-described system including at least one syringe and at least one piston for releasably holding the plunger of a syringe engaged with the fluid injector described herein with reference to FIGS. 1-2 is disclosed in Patent Document 1, and another aspect of a related multi-fluid delivery system that can be modified for use with the present system is found in Patent Document 2, Patent Document 3, International Application US2012 / 037491, and Patent Document 4, the disclosures of each of which are incorporated herein by reference. Other embodiments can include new fluid injector systems designed to include various embodiments of the connection interface between the piston 13 of the injector 10 described herein and the plunger 26 of the syringe 12.

[0151] Referring to FIG. 3, a representative embodiment of a dual syringe angiography injector system 100 (hereinafter referred to as "injector 100") is shown. The injector 100 is configured to inject two medical fluids through a first fluid path 17A for a medical fluid, such as a radiographic 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. The injector 100 can include an injector housing 14 having two syringe ports 16 configured to engage two syringes 12.

[0152] The injector housing 14 can further include at least one user interface 11 through which an operator can visually recognize and control the state of the injection process. The user interface 11 can be operably communicated with a controller (similar to the controller 200 described herein, FIG. 2) that transmits and receives commands to and from the user interface 11.

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

[0154] Continuing to refer to FIG. 3, the injector 100 can further include bulk fluid containers 19A and 19B for filling and refilling each syringe 12 with a contrast medium and a flushing fluid, respectively. The bulk fluid containers 19A and 19B can be selectively fluidly communicated with the syringes 12 via respective bulk fluid paths 21A and 21B and bulk fluid valves 23A and 23B.

[0155] Further details and examples of a suitable non-limiting electric injector system including a syringe, a controller, and an air detector are described in Patent Documents 1, 2, 3, 5, 6, and 7, the disclosures of which are hereby incorporated by reference in their entirety. Although the injector 100 is described herein in the context of a dual syringe angiography (CV) injector, it should be understood that the injector 100 can be adapted to single and multiple syringe configurations for any injection procedure (e.g., CT, PET, MRI, ultrasound, etc.).

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

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

[0158] After the filling and priming operations, the controller may be programmed or configured to perform a delivery operation in which the piston associated with one or both of the syringes 12 is moved toward the distal end of the syringe 12 to inject the infusion fluid into the first fluid path 17A and the second fluid path 17B. The controller may be programmed or configured to selectively activate 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 fluid path 17A and the second fluid path 17B may converge at a fluid mixing connector that provides turbulent mixing between the first fluid and the second fluid, such as the fluid mixing connectors described in International Application No. US2021 / 019507 and International Application No. US2014 / 026324, the disclosures of which are incorporated herein by reference.

[0159] Referring now to FIG. 4, there is shown 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. In some embodiments, controller 200 may include additional components, fewer components, different components, or components in a different arrangement than those shown in FIG. 4. Controller 200 can 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). Bus 202 can include components that permit communication between the components of controller 200. In some non-limiting embodiments, at least one processor 204 may be implemented in hardware, firmware, or a combination of hardware and software. For example, at least one processor 204 can include a processor (such as 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 execute functions (such as a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), etc.). Memory 206 can include random access memory (RAM), read only memory (ROM), and / or other types of dynamic or static storage devices (such as flash memory, magnetic memory, optical memory, etc.) that store information and / or instructions for use by at least one processor 204.

[0160] The memory component 208 can store information and / or software related to the operation and use of the controller 200. For example, the memory 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 via user input (such as a GUI, touch screen display, keyboard, keypad, mouse, button, switch, microphone, etc.). Additionally or alternatively, the input component 210 may include sensors for detecting information (such as a global positioning system (GPS) component, accelerometer, gyroscope, actuator, etc.). The output component 212 can include components that provide output information from the controller 200 (such as a GUI, display, speaker, one or more light-emitting diodes (LEDs), etc.). The communication interface 214 can include components such as a transceiver (such as a transceiver, separate receiver and transmitter, etc.) that enable the controller 200 to communicate with other devices via a wired connection, wireless connection, or a combination of wired and wireless connections. The communication interface 214 can allow the controller 200 to receive information from another device and / or provide information to another device. The input component 210, output component 212, and / or communication interface 214 may correspond to or be components of the user interface 11 (see FIG. 3).

[0161] The controller 200 can execute the methods described herein based on at least one processor 204 that executes software instructions stored by a computer-readable medium such as the memory 206 and / or the storage component 208. The computer-readable medium can include any non-transitory memory device. The memory device can include a memory space located within a single physical memory device or a memory space that spans multiple physical memory devices. The software instructions may be read into the memory 206 and / or the 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 the storage component 208 can cause the processor 204 to execute one or more of the processes described herein. Additionally or alternatively, instead of or in combination with software instructions, hardwired circuitry may be used to execute one or more of the processes described herein.

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

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

[0164] Referring to FIG. 5A, in some embodiments, the proximal end 320 of the syringe 300 is sized and adapted to be removably inserted into the syringe port of the injectors 10, 100 (shown in FIGS. 1 and 3) or inserted into a pressure jacket (not shown) engaged with the fluid injector. The proximal end 320 of the syringe 300 can define an insertion section 330 that is removably inserted into the syringe port of the injector 10 shown in FIG. 1 or the injector 100 shown in FIG. 3, while the remaining portion of the syringe 300 remains outside the syringe port. In another embodiment, the syringe 300 is inserted into a hole in the pressure jacket and may be releasably held within one or more retaining features, as described in International Application No. 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 within the syringe ports of the injectors 10, 100 to releasably hold the syringe 300 within the syringe ports. Suitable non-limiting configurations for the retaining members to releasably lock the syringe 300 to the injectors 10, 100 are described in Patent Documents 8 and 9, the entire disclosures of which are incorporated herein by reference. The syringe 300 is omitted from many of the figures of the corresponding plunger engagement mechanisms of the present disclosure for clarity.

[0165] Referring to FIGS. 6-8C, a plunger 326 according to an embodiment of the present disclosure is shown. The plunger 326 includes a plunger body 332 that defines a plunger longitudinal axis 334 and has 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 can have a uniform or non-uniform thickness between the proximal end 336 and the distal end 338. At least a portion of the sidewall 339 may be conical. The plunger body 332 may be formed of glass, metal, or a suitable medical plastic.

[0166] The plunger body 332 has an internal cavity 340 (FIG. 7) having a conical portion 342 at the distal end 338 of the plunger body 332 and a cylindrical portion 344 at the 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 attached or separately fixed to the cylindrical portion 344 of the plunger body 332, for example, using friction fit and / or adhesives, welding, or by molding. The conical portion 342 can have a frustoconical 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 that projects in a radially outward direction with respect to the longitudinal axis 334. In this way, the ledge 345 divides the cylindrical portion 344 into a first portion 347a having a first inner diameter and a second portion 347b having a second inner diameter that is larger than the first inner diameter.

[0167] Referring to FIG. 7, the plunger 326 can have one or more release tabs 380 that project from the inner surface 352 of the internal cavity 340 of the plunger body 332. In some embodiments, the one or more release tabs 380 may project radially inwardly from at least a portion of the inner surface 352 of the cylindrical portion 344 of the plunger body 332, such as a first portion 347a. The one or more release tabs 380 may be configured to interact with at least a portion of the plunger engagement mechanism 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 plurality of release tabs 380 may be radially separated with respect to the plunger longitudinal axis 334 along the outer periphery of the inner surface 352 of the internal cavity 340. In such embodiments, the release tabs 380 are separated from each other 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 each other. In some embodiments, the release tabs 380 may have a non-uniform angular spread and / or a non-uniform angular spacing between the retaining ribs 350 around the inner surface 352 of the internal cavity 340. The proximal end 382 of each release tab 380 can have a pointed or angled guide surface 384 configured to orient the plunger 326 with respect to at least a portion of the plunger engagement mechanism, as according to the particular embodiments described herein.

[0168] Referring to FIG. 6, the plunger 326 can have a plunger cover 357 having an elastic seal 358 that covers at least a portion of the outer surface 360 of the plunger body 332. The seal 358 can be a flexible seal that engages the inner surface 323 (shown in FIG. 5B) of the syringe barrel 318 such that the seal 358 liquid-tightly seals the internal volume 325 of the syringe barrel 318. The seal 358 can be provided separately from the plunger body 332 or can be formed integrally with the plunger body 332, such as by co-molding. 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 slidably engage the inner surface of the syringe barrel 318. In some embodiments, at least the sealing element 366 of the seal 358 can be made of an elastomeric material that elastically 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 deviating from axial alignment with the syringe 300 when the plunger 326 is moved through the syringe barrel 318.

[0169] Referring to FIG. 7, plunger 326 can have at least one resiliently deflectable retaining member 368 (hereinafter, “retaining member 368”) that projects proximally from plunger body 332. In some embodiments, at least one retaining member 368 may project proximally from inner surface 352 of inner cavity 340 of plunger body 332. At least one retaining member 368 has a first distal end 370 connected to plunger body 332 and a second proximal end 372 that is deflectable radially with respect to first end 370 in a direction toward longitudinal axis 334 and / or away from the bottom. As described herein, second end 372 may be deflectable radially with respect to first end 370 when at least one retaining member 368 engages at least a portion of the plunger engagement mechanism on the piston of injectors 10, 100 (FIGS. 1 and 3). That is, when the portion of the plunger engagement mechanism is moved distally into contact with retaining member 368, retaining member 368 is deflected radially by the portion of the plunger engagement mechanism. Similarly, during disengagement of the piston from the plunger, when the portion of the plunger engagement mechanism is moved proximally into contact with retaining member 368, retaining member 368 is deflected radially by the portion of the plunger engagement mechanism. First end 370 and second end 372 may be spaced apart in a direction extending substantially along the direction of plunger longitudinal axis 334 of plunger 326. At least one retaining member 368 may be continuously linear or curved between first end 370 and second end 372. In some embodiments, one or more retaining members 368 may extend in a direction parallel to the direction of plunger longitudinal axis 334. In another embodiment, one or more retaining members 368 may extend in a direction inclined with respect to the direction of plunger longitudinal axis 334. For example, one or more retaining members 368 may be inclined toward or away from plunger longitudinal axis 334 in a direction extending from proximal end 336 to distal end 338 of plunger body 332.

[0170] In some embodiments, the plurality of retaining members 368 are radially spaced from the plunger longitudinal axis 334 along the outer periphery of the inner surface 352 of the internal cavity 340. In such embodiments, the retaining members 368 are separated from each other by portions of the inner surface 352 of the internal cavity 340. In embodiments where three or more retaining members 368 are provided, the retaining members 368 may be evenly spaced from each other. For example, in one exemplary and non-limiting aspect having six retaining members 368 with equal angular separation, such as shown in FIGS. 7-8C, each retaining member 368 is 60 degrees away from the retaining members 368 adjacent on both sides. 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 outer 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 projects radially from the retaining member 368. The at least one catch 374 is configured to interact with a portion of the plunger engagement mechanism such that the second end 372 is deflected when a portion of the plunger engagement mechanism passes by the at least one catch 374. In some embodiments, the at least one catch 374 may project radially inwardly toward the plunger longitudinal axis 334 of the plunger body 332. In this way, the at least one retaining member 368 is configured to deflect radially outwardly by 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 project radially outwardly away from the plunger longitudinal axis 334 of the plunger body 332. In this way, the at least one retaining member 368 is configured to deflect radially inwardly by contact between the catch 374 and at least a portion of the plunger engagement mechanism on the piston, as described herein. The at least one retaining member 368 is configured to return toward its non-deflected state by moving radially inwardly.

[0172] At least one catch 374 may be integrally formed with the second end 372 of at least one retaining member 368, or may be affixed or separately secured to the second end 372 of at least one retaining member 368, for example, using friction fitting and / or adhesives, welding, or by co-molding. In another embodiment, at least one catch 374 may be formed on the second end 372 of at least one retaining member 368 by etching, laser cutting, or machining. As described herein, at least one 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 injectors 10, 100 to lock at least one retaining member 368 against the piston when the plunger engagement mechanism is in a locked state or position by an embodiment of the mechanism described herein. As shown in FIGS. 7 - 8C, the catch 374 can have a distal surface 377 with a rounded edge. In some embodiments, the catch 374 can have a proximal surface 379 with a rounded edge. The shapes of the distal surface 377 and the proximal surface 379 may be such that the catch 374, by itself, is unable to form a locking engagement with a corresponding locking feature on the plunger engagement mechanism of the piston. Instead, the catch 374 must act in concert with the operation of the plunger engagement mechanism to form a locking engagement with the piston.

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

[0174] Referring to FIGS. 8A - 8C, the plunger 326 can have one or more release tabs 380 projecting from at least a portion of the inner surface 352 of the cylindrical portion 344 of the plunger body 332, such as a second portion 347b. The one or more release tabs 380 may project axially and radially inwards from the ledge 345 and the inner surface 352 of the second portion 347b of the cylindrical portion 344, either 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 the plunger engagement mechanism on the piston to cause release of the plunger 326 from the piston when the plunger 326 rotates about its longitudinal axis 334, such as by rotation of the syringe 300.

[0175] The embodiment of the plunger 326 of FIG. 8C has at least one retaining member 368 having a catch 374 projecting radially outwards in a direction away from the plunger longitudinal axis 334. Thus, the at least one retaining member 368 shown in FIG. 8C is configured to deflect radially inwards by contact between the catch 374 and at least a portion of the plunger engagement mechanism on the piston, as described herein. The at least one retaining member 368 shown in FIG. 8C is configured to return towards its non - deflected state by moving radially outwards.

[0176] Referring to FIG. 9, an embodiment of the piston 400 is shown separately from the injector. In another embodiment, the piston 400 may be configured to be used 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 can 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 the plunger.

[0177] Referring to FIG. 9, the piston 400 has a body 404 and a piston head 406 at the 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 outwardly beyond the radial edge of the body 404. The piston 400 is constructed from a relatively rigid material such as a metal, plastic, or combination thereof that can withstand 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 inner cavity 340 (FIG. 8C) of the plunger 326. In some embodiments, at least a portion of the piston head 406 may be made of 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 at least a portion of the plunger 326 and / or the syringe 300.

[0178] In some embodiments, a sensing member such as a spring pin (see, e.g., pin 707, FIGS. 21A-21B) connected to the sensor may be provided. The sensing member can extend along the longitudinal axis of the piston 400 and can protrude through at least a portion of the piston head 406. The sensing member operates to detect contact with a surface such as surface 348 of the plunger 326 and can control the movement of the piston 400 based on the detected condition. For example, the first contact between the sensing member and surface 348 of the plunger 326 can cause the pin to retract in the proximal direction so as to contact the sensor. The sensor may be connected to the drive mechanism of the piston 400 such that when the sensor is actuated by the pin, the sensor controls the movement of the drive mechanism. For example, the drive mechanism may be stopped or decelerated 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 with the plunger 326 to facilitate reciprocating actuation of the plunger 326 within the barrel of the syringe 300 (Figs. 5A-5B). Continuing to refer 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 the longitudinal piston axis 420. The plunger engagement post 418 is reciprocally actuated 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 retaining member 368 associated with the plunger 326 within the 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 disposed relative to the plunger engagement sleeve 414 to permit removal of at least one retaining member 368 associated with the plunger 326 from the receiving space 415 between the plunger engagement sleeve 414 and the plunger engagement post 418. Fig. 9 shows portions of the plunger engagement mechanism 412 in the engaged position or state and the disengaged position or state. Specifically, the plunger engagement post 418 of Fig. 9 is shown in both its engaged position or state (right side of the cross-section) and its disengaged position or state (left side of the cross-section). During 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 movable linearly and / or rotationally relative to the piston 400.

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

[0181] Referring to FIG. 10B, a portion of the inner surface 428 of the central opening 416 at the distal end of the opening 416 can have an inclined portion 430 such that the inner diameter of the opening 416 tapers in a direction from the distal end 426 of the hollow body 424 toward the proximal portion or end 432. The inclined portion 430 can be configured to engage the catch 374 and deflect at least one retaining member 368 associated with the plunger 326 radially inwardly during connection of the plunger 326 to the distal portion or end 426 of the plunger engagement sleeve 414. The inclined portion 430 can terminate in a locking rib 434. At least one catch 374 can be configured to bend easily and abut against the proximal face of the locking rib 434 such that the at least one catch 374 can pass through the locking rib 434 easily when the piston moves in the proximal direction, so long as the plunger engagement mechanism 412 does not move to a locked engagement configuration. That is, the at least one retaining member 368 and the corresponding catch 374 can bend easily and move inside and outside the central opening 416 of the plunger engagement sleeve 414 when the piston is in a 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 at least one catch 374 on 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 locked engagement with the plunger engagement mechanism 412, as described herein. The inner surface 428 of the central opening 416 can be substantially cylindrical proximal to the locking rib 434.

[0182] The 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 the guide pin 439 of the plunger engagement post 418 (FIG. 9). The longitudinal groove 438 has a distal stop 440 for defining the distal movement of the guide pin 439, thereby delimiting the distal movement of the plunger engagement post 418 relative to the plunger engagement sleeve 414. The 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] Referring to FIGS. 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 the 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 engage the male threaded connector 450 on the actuator 422. In another embodiment, the connecting member 448 may be an adhesive, clip, press fit, fastener, or any other connector feature for removably or non-removably connecting the housing 446 to the connector 450 on the actuator 422.

[0184] Referring to FIGS. 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 an outer diameter smaller than that of 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 the 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] The plunger release sleeve 458 surrounds the distal portion 454 of the housing 446. In some embodiments, the plunger release sleeve 458 has a cylindrical side wall 460 through which an opening 462 passes. The opening 462 can have a longitudinal plane 463 that is substantially parallel to the longitudinal axis 464 of the plunger release sleeve 458 and an inclined plane 466 that is adjacent to the longitudinal plane 463 and is inclined with respect to the longitudinal axis 464 of the plunger release sleeve 458 in a direction from the distal end 468 to the proximal end 470. As described herein, the longitudinal plane 463 is configured to guide the guide pin 439 of the plunger engagement post 418 (FIG. 9) during the longitudinal movement of the plunger engagement post 418 along the longitudinal axis 420 of the piston 400, while the inclined plane 464 is configured to guide the guide pin 439 during the rotational movement of the plunger 326 with respect to the piston 400, such as during the 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] Referring to FIG. 11B, the actuator 422 can 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 automatically move to the disengaged state, such as during a power loss to the actuator 422. In some embodiments, the actuator 422 may only become engaged during the proximal movement of the piston 400. In some embodiments, the actuator 422 may be a solenoid configured to be mainly in the disengaged state, and may only be in the engaged state during the 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 backdriven in the event of a power loss to the injector.

[0187] Referring to FIG. 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 a clockwise direction and a counterclockwise direction, or in one of the clockwise and counterclockwise directions. The plunger engagement sleeve 414 may be rotatable from the first position to the second position by the 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 the interaction of the release tab 390 on the plunger 326 with the toothed portion 444 on the piston engagement sleeve 414. In certain embodiments, the rotation of the plunger engagement sleeve 414 can move the guide pin 439 along the inclined surface 466 of the plunger release sleeve 458 to move the plunger engagement post 418 to a disengaged position or an engaged position. A biasing member 496 may be provided to bias the plunger engagement sleeve 414 to the first position. In this way, when the plunger engagement sleeve 414 is rotated from the first position toward the second position, the biasing member 496 builds up potential energy, which is then used to assist in returning the plunger engagement sleeve 414 to the first position. In some embodiments, the biasing member 496 may be a torsion spring having one end connected to the plunger engagement sleeve 414 and the other end connected to the housing 446 or the plunger release sleeve 458.

[0188] Referring to FIG. 12, the plunger engagement post 418 is shown separately from the plunger engagement mechanism 412. The plunger engagement post 418 has a shaft 472 with a proximal end 474 and a distal end 476. The distal end 476 of the shaft 472 has a tapered end face 478 configured to contact at least one flexible retaining member 368 on the plunger 326 when the plunger engagement post 418 is in the engaged position to lock at least one catch 374 to 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 (shown in FIGS. 10A - 10B) of the plunger engagement sleeve 414. 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 the longitudinal axis 482 of the shaft 472. An elastic resilient member 484 surrounds the shaft 472 and has a distal end 486 that abuts a ledge 488 at the distal end 478 of the shaft 472. The proximal end 490 of the elastic resilient member 484 may be configured to contact the actuator 422 or the housing 446. The elastic resilient member 484 may be a compression spring configured to bias the plunger engagement post 418 in the distal direction toward the engaged position as described herein. In another embodiment, the elastic resilient member 484 may be a tension spring configured to bias the plunger engagement post 418 in the proximal direction toward the disengaged position.

[0190] Although the structure of the plunger 326 and the piston 400 according to a non - limiting embodiment of the present disclosure has been described, here, a method of engaging and disengaging the plunger 326 with respect to the piston 400 will be described with reference to FIGS. 13A - 13J.

[0191] FIG. 13A shows the piston 400 before it is connected to the plunger 326 with its plunger engagement mechanism 412 in the engaged position or state. In some embodiments, the default state of the plunger engagement mechanism 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 the connection of the syringe 300 to the injector 10, 100, the piston 400 is drawn into the housing of the injector 10, 100. After connecting the syringe 300 to the injector 10, 100, the piston 400 can advance distally towards the plunger 326.

[0192] Referring to FIG. 13B, the actuator 422 is energized to retract the shaft 472 of the plunger engagement post 418 from the engaged position or state to the disengaged position or state in the proximal direction indicated by arrow A. The movement of the shaft 472 in the proximal direction opens the receiving space 415 between the plunger engagement sleeve 414 and the plunger engagement post 418 to allow the insertion or removal of one or more retaining members 368 of the plunger 326 into the receiving space 415. Such movement also compresses the resilient elastic member 484 between the ledge 488 at the distal end of the shaft 472 and the actuator 422. The compression of the resilient elastic member 484 builds potential energy therebetween and can then be used to guide the plunger engagement post 418 towards the engaged position or state when released.

[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 the engaged position or state to the disengaged position or state in the proximal direction indicated by arrow A by the elastic restoring force of the elastic resilient member 484. In such an embodiment, the elastic resilient member 484 may be a tension spring that is stretched from a first state to a second state by the actuation of the actuator 422. When the actuator 422 is de-energized, the restoring force of the elastic resilient member 484 forces the plunger engagement post 418 toward the disengaged position or state. In this way, the plunger engagement post 418 is normally in the disengaged position or state, thereby allowing the removal of the plunger 326 from the piston 400 in the event that the actuator 422 cannot operate due to power loss or the like.

[0194] Referring to FIG. 13C, the piston 400 can then move axially in the distal direction toward the plunger 326 (shown 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 manually moved in the distal direction.

[0195] Referring to FIG. 13D, the piston 400 is advanced axially in the distal direction such that at least one retaining member 368 of the plunger 326 is received within the central opening 416 of the plunger engagement sleeve 414. Initially, the inner surface 428 of the central opening 416 contacts the catch 374 of the at least one retaining member 368. Since the catch 374 projects radially outwardly 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 inclined portion 430 of the central opening 416. In this way, continued distal movement of the piston 400 deflects the at least one retaining member 368 radially inwardly by the contact between the catch 374 and the inclined portion 430. In embodiments having a plurality of retaining members 368, each of the retaining members 368 is deflected radially inwardly.

[0196] During continuous axial movement of the piston 400 in the distal direction, the catch 374 is deflected above 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 by contact between the 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 at least one retaining member 368 can be elastically deflected radially inwardly such that the catch 374 is disposed proximally relative to 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. While at least one retaining member 368 is in the position shown in FIG. 13D, the at least one retaining member 368 can be deflected radially inwardly with proximal movement of the piston 400 or distal movement of the plunger 326 (such as by removal of the syringe from the injector), so 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 a toothed portion 444 on the outer surface 442 of the plunger engagement sleeve 414. In certain embodiments, the plunger 326 cannot be in an engaging and locking position with the piston 400 while the piston 400 is moving distally and only moves to the engaging and locking position upon proximal movement of the piston 400. Such a feature can enable easy removal of the syringe 300 and the plunger 326 after short distal movement of the piston 400 and can reduce wear of system components and / or the motor by requiring locking engagement only when the piston 400 is retracting.

[0197] Referring to FIG. 13E, the actuator 422 is de-energized to allow the shaft 472 of the plunger engagement post 418 to move from the disengaged position or state, indicated by arrow C, to the engaged position or state. In another embodiment, the actuator 422 may be energized to move the shaft 472 of the plunger engagement post 418 distally.

[0198] The distal movement of the shaft 472 closes the receiving space 415 between the plunger engagement sleeve 414 and the plunger engagement post 418, which latches at least one catch 374 to the locking rib 434 to prevent removal of one or more retaining 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 the disengaged position or state to the engaged position or state by release of the potential energy stored in the resilient elastic member 484. In another embodiment, the plunger engagement post 418 moves from the disengaged position or state to the engaged position or state by actuation of the actuator 422, building potential energy within the resilient elastic member 484. When the plunger engagement post 418 moves to the engaged position or state, at least one retaining 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 the connected plunger 326 can then reciprocate within the barrel 318 of the syringe (FIGS. 5A-5B). In certain embodiments, the piston 400 and the connected plunger 326 can move proximally within the barrel 318 and can move distally when the piston 400 is in either the engaged or disengaged position with the plunger 326. In some embodiments, the piston 400 can advance distally to deliver fluid from the syringe 300 or proximally to fill the syringe 300 with fluid using a drive mechanism 402 operated by the controller 200 (FIG. 2).

[0199] In certain embodiments involving manual disengagement of the syringe, to unlock the syringe 300 from the syringe port of the injector and disengage the plunger 326 from the piston 400, the syringe 300 can be rotated clockwise or counterclockwise about the syringe longitudinal axis relative to the syringe port. Since there is substantially no rotation of the plunger 326 due to frictional interaction with the syringe barrel 318, the rotation of the syringe 300 also rotates the plunger 326 relative to the piston 400 about the longitudinal piston axis 420. 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 also causes the rotation of the plunger 326 to rotate 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. Since the guide pin 439 on the plunger engagement post 418 is received within the longitudinal groove 438 of the plunger engagement sleeve 414, the plunger engagement post 418 also rotates with the rotation of the plunger engagement sleeve 414. Rotation of the plunger engagement post 418 guides the guide pin 439 along the inclined 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 within the biasing member 496.

[0200] In another embodiment, such as when the syringe is housed within the 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 electro-mechanical actuator to disengage the plunger 326 from the piston 400. As described herein, a motor such as a linear or rotary electric motor, or an electric actuator such as a solenoid, 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 with respect 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] Referring to FIG. 13G, movement of the guide pin 439 along the inclined surface 466 of the plunger release sleeve 458 axially moves the plunger engagement post 418 in the proximal direction of arrow D from the engaged position or state to the disengaged position or state. In some embodiments, the plunger engagement post 418 can be moved in the proximal direction by applying energy to the actuator 422 to retract the shaft 472 of the plunger engagement post 418. In this way, the plunger engagement post 418 can be moved manually, such as via rotation of the plunger 326 with respect 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 allow removal of one or more retaining members 368 of the plunger 326 from the receiving space 415. Further, a configuration that requires only actuation of the actuator 422 can reduce wear of system components and / or motors by requiring only a locking engagement when the piston 400 is moving in the proximal direction.

[0202] When the plunger engagement mechanism 412 is in the 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 to remove the syringe 300 and the plunger 326 from the fluid injector. During such relative movement of the piston 400 relative to the plunger 326 in a direction away from each other, the catch 374 is deflected above the locking rib 434 of the piston engagement sleeve 414 to allow removal of one or more retaining members 368 from the piston 400. The plunger 326 can then be freely detached from the piston 400 as shown in FIG. 13H.

[0203] Referring to FIGS. 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 a second position to a first position about the longitudinal piston axis 420 (shown in FIG. 9) by the restoring force provided by the biasing member 496. Movement of the plunger engagement sleeve 414 and the plunger engagement post 418 to the first position guides the guide pin 439 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. Thereby, the plunger engagement post 418 moves in the distal direction of arrow E. The position of the plunger engagement mechanism 412 in FIG. 13J is the same as the position of the plunger engagement mechanism 412 in FIG. 13A.

[0204] Referring to FIGS. 14A - 14C, a piston 500 and a plunger engagement mechanism 512 according to another embodiment of the present disclosure are shown. The components of the piston 500 and the plunger engagement mechanism 512 shown in FIGS. 14A - 14C are substantially similar or identical to the components of the piston 400 and the plunger engagement mechanism 412 described herein with reference to FIGS. 9 - 13J. Therefore, the reference numerals in FIGS. 14A - 14C are used to indicate the same components as the corresponding reference numerals in FIGS. 9 - 13J, except that the leading digit of the reference numerals used in FIGS. 14A - 14C has been changed from "4" to "5". For example, the piston described in relation to FIGS. 9 - 13J is designated by the reference numeral "400", while the piston in FIGS. 14A - 14C is identified by the reference numeral "500". The foregoing description regarding the piston 400 and the plunger engagement mechanism 412 shown generally in FIGS. 9 - 13J is applicable to the piston 500 and the plunger engagement mechanism 512 shown in FIGS. 14A - 14C, so only the relative differences between the components shown in these figures are described below.

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

[0206] Continuing to refer to FIG. 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 has a proximal portion 519 rotatably connected to a plunger release sleeve 558 such that the plunger engagement post 518 is rotatable about the longitudinal piston axis 520. Referring to FIG. 15, the proximal portion 519 can have 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 has 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 single piece. One or more openings 523 may be formed in the plunger engagement post 518 through a connecting piece 525 that connects 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. The 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 defining the distal movement of the guide pin 539, thereby delimiting the distal movement of the plunger engagement sleeve 514 relative to the plunger engagement post 518.

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

[0208] Continuing to refer to FIG. 15, the post portion 521 of the plunger engagement post 518 has a locking groove 527 configured to receive a catch 374 of at least one flexible retaining member 368 of the plunger 326. The distal end of the post portion 521 may be shaped to deflect at least one retaining member 368 radially outwardly by contact of the catch 374 with the outer surface of the post portion 521. In certain embodiments, the distal end of the post portion 521 can include an inclined portion for further deflecting at least one retaining member 368 radially outwardly. In this way, distal movement of the piston 500 relative to the plunger 326 deflects at least one retaining member 368 radially outwardly by contact between the catch 374 and the outer surface of the post portion 521. In embodiments having a plurality of retaining members 368, each of the retaining members 368 is deflected radially outwardly.

[0209] Referring to FIG. 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. Referring to FIG. 16, the plunger release sleeve 558 has a cylindrical side wall 560 through which an opening 562 extends. The opening 562 can have a longitudinal plane 563 that is substantially parallel to the longitudinal axis 564 of the plunger release sleeve 558, and an inclined plane 566 that is adjacent to the longitudinal plane 563 and is inclined with respect to the longitudinal axis 564 of the plunger release sleeve 558 in a direction from the distal end 568 to the proximal end 570. As described herein, the longitudinal plane 563 is configured to guide the guide pin 539 (FIG. 14A) during longitudinal movement of the plunger engagement sleeve 514 along the longitudinal axis 520 of the piston 500, while the inclined plane 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] Referring to FIGS. 17A - 17B, the plunger engagement sleeve 514 is shown separately 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 in the proximal portion 519 of the plunger engagement post 518. The distal portion or end 526 of the plunger engagement sleeve 514 is received through the opening 523 (FIG. 15) of the plunger engagement post 518 and is shaped to be disposed within the internal cavity 340 (FIGS. 14A - 14B) of the plunger 326. At least a portion of the plunger 326, such as at least one retaining member 368, is configured to be received within the central opening 516 and within the receiving space 515 between the 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 can have an inclined portion 530 such that the inner diameter of the opening 516 tapers in a direction from the distal end 526 of the hollow body towards the proximal portion or end 532. The inclined portion 530 is configured to deflect at least one retaining member 368 associated with the plunger 326 radially inwards during connection of the plunger 326 to the piston 500, creating a tight engagement interaction between the catch 374 of at least one flexible retaining member 368 and the locking groove 527 of the plunger engagement post 518.

[0211] Continuing to refer to FIGS. 17A - 17B, the hollow body 524 of the plunger engagement sleeve 514 has a through - hole 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 the inclined surface 566 of the plunger release sleeve 558 due to rotation of the plunger 326 and the plunger engagement post 518.

[0212] Although the structure of the plunger 326 and the piston 500 according to a non - limiting embodiment of the present disclosure has been described, here, a method of engaging and disengaging the plunger 326 with respect to the piston 500 will be described with reference to FIGS. 14A - 14C.

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

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

[0215] Referring to FIGS. 14A and 14C, the plunger engagement sleeve 514 moves from the disengaged position or state to the engaged position or state. Such movement of the plunger engagement sleeve 514 can be due to the actuator being de-energized and an elastic elastic member such as the elastic elastic member 484 described herein with reference to FIGS. 9-13J forcing the plunger engagement sleeve 514 axially in the distal direction. In another embodiment, such movement of the plunger engagement sleeve 514 can be due to the application of energy to the actuator for forcing the plunger engagement sleeve 514 axially in the distal direction. For example, the actuator may be actuated by a rotary motor or a linear motor to move the actuator from the disengaged position to the engaged position in the distal direction. By applying energy to the actuator in this way, the plunger engagement sleeve 514 is moved in the distal direction to build the elastic restoring force of the elastic elastic member. The distal movement of the plunger engagement sleeve 514 closes the receiving space 515 between the plunger engagement sleeve 514 and the plunger engagement post 518 to prevent the removal of one or more of the retaining members 368 of the plunger 326 from the receiving space 515 and the catch 374 of one or more flexible retaining members 368 and locking grooves 527. When the plunger engagement sleeve 514 moves to the engaged position or state, 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 the connected plunger 326 can then reciprocate within the barrel 318 of the syringe 300.

[0216] To unlock the syringe 300 from the syringe port of the injector 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. Since there is substantially no rotation within the syringe barrel 318 by the frictional force, the rotation of the syringe 300 also rotates the plunger 326 relative to the piston 500 about the longitudinal piston axis 520. Alignment of one or more release tabs 380 on the plunger 326 with the toothed portion 544 on the plunger engagement post 518 also rotates the plunger engagement post 518 from a first position to a second position relative to the plunger release sleeve 558. Since the guide pin 539 on the plunger engagement sleeve 514 is received within the longitudinal groove 538 of the plunger engagement post 518, the plunger engagement sleeve 514 also rotates with the rotation of the plunger engagement post 518. The rotation of the plunger engagement sleeve 514 guides the guide pin 539 along the inclined surface 566 of the plunger release sleeve 558 (see FIG. 16) and moves the plunger engagement sleeve 514 proximally to compress the resilient elastic member, similar to the operation of the resilient elastic member 484 described herein with reference to FIGS. 9-13J. Additionally, the rotation of the plunger engagement post 518 about the longitudinal piston axis 520 can build the potential energy of the biasing member, similar to the operation of the biasing member 496 described herein with reference to FIGS. 9-13J.

[0217] The movement of the guide pin 539 along the inclined surface 566 of the plunger release sleeve 558 axially moves the plunger engagement sleeve 514 in the proximal direction from the engaged position or state to the disengaged position or state shown in FIG. 14A. In some embodiments, the plunger engagement sleeve 514 can move in the proximal direction by applying energy or cutting off energy to the actuator to retract the plunger engagement sleeve 514. The proximal movement of the plunger engagement sleeve 514 allows the removal of one or more flexible retaining members 368 and the catch 374 of the locking groove 527, and opens the receiving space 515 between the plunger engagement sleeve 514 and the plunger engagement post 518 to enable the removal of one or more retaining members 368 of the plunger 326 from the receiving space 515.

[0218] Referring to FIGS. 18A-18B, a piston 600 and a plunger engagement mechanism 612 according to another embodiment of the present disclosure are shown. The components of the piston 600 and the plunger engagement mechanism 612 shown in FIGS. 18A-18B are substantially similar or identical to the components of the piston 400 and the plunger engagement mechanism 412 described herein with reference to FIGS. 9-13J. Accordingly, the reference numerals of FIGS. 18A-18B are used to indicate the same components of FIGS. 9-13J, except that the leading digit of the reference numerals used in FIGS. 18A-18B has been changed from "4" to "6". For example, the piston described in connection with FIGS. 9-13J is designated by the reference numeral "400", while the piston of FIGS. 18A-18B is identified by the reference numeral "600". The foregoing description of the piston 400 and the plunger engagement mechanism 412 shown generally in FIGS. 9-13J is applicable to the piston 600 and the plunger engagement mechanism 612 shown in FIGS. 18A-18B, and only the relative differences between the components shown in these figures are described below.

[0219] Referring to FIG. 18A, the plunger engagement mechanism 612 has a plunger engagement sleeve 614 with a central opening 616 and a plunger engagement post 618 that is reciprocally movable within the central opening 616 of the plunger engagement sleeve 614 along the direction of the 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 backdriven in the event of a power loss 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 at least one retaining 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 proximal to the plunger engagement sleeve 614 to allow removal of at least one retaining member 368 associated with the plunger 326 from the receiving space 615 between the plunger engagement sleeve 614 and the plunger engagement post 618.

[0221] Continuing to refer to FIG. 18A, the plunger engagement sleeve 614 has a hollow body 624, and at least a portion of the outer surface of the hollow body 624 defines at least a portion of the piston head 606. The distal portion or end 626 of the plunger engagement sleeve 614 is shaped to be received within the internal cavity 340 of the plunger 326, while at least a portion of the plunger 326, such as at least one retaining member 368, is configured to be received within the central opening 616. The central opening 616 extends through the hollow body 624 of the plunger engagement sleeve 614. The inner surface of the central opening 616 can have an inclined portion 630 such that the inner diameter of the opening 616 tapers in a direction from the distal end to the proximal portion or end of the hollow body 624. The inclined portion 630 is configured to deflect at least one retaining member 368 associated with the plunger 326 radially inwardly during connection of the plunger 326 to the plunger engagement sleeve 614 by contacting a catch 374 of one or more flexible retaining members 368 as the piston head 606 moves distally relative to the plunger 326. The inclined portion 630 may terminate in a locking rib 634. The outer surface 642 of the plunger engagement sleeve 614 can 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] Referring to FIG. 18B, the plunger engagement post 618 is shown separately from the plunger engagement mechanism 612. The plunger engagement post 618 has a shaft 672 with a proximal end 674 and a distal end 676. The distal end 676 of the shaft 672 has a tapered end face 678 configured to contact at least one retaining member 368 on the plunger 326 when the plunger engagement post 618 is in the 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 the engaged position or state and the disengaged position or state.

[0223] Continuing to refer to FIG. 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 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 linearly or curvilinearly continuous between a ledge 679 near the proximal end 674 of the shaft 672 and the distal end 676. 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] Continuing to refer to FIG. 18B, the plurality of grooves 665 are radially spaced from the longitudinal axis 667 along the outer periphery of the distal end 676 of the shaft 672. In embodiments where three or more grooves 665 are provided, the grooves 665 are equally spaced from each other and separated from each other 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 and non-limiting aspect having six retaining members 368 with equal angular separation as shown in FIG. 8C, the corresponding plunger engagement posts 618 have six grooves 665 that are 60 degrees apart from the grooves 665 adjacent on both sides.

[0225] Referring to FIG. 18A, the proximal end 674 of the shaft 672 is received in a rotation mechanism 671 that is slidably mounted within the hollow body 624 of the plunger engagement sleeve 614. In some embodiments, the rotation mechanism 671 includes a first portion 673 that is slidably mounted within the hollow body 624 and fixed so as not to rotate relative to the plunger engagement sleeve 614, and a second portion 675 that is fixed to the plunger engagement post 618 and is 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 clockwise or counterclockwise about the longitudinal axis 620. For example, the rotation mechanism 671 may be a one-way clutch.

[0226] Although the structure of the plunger 326 and the piston 600 according to a non-limiting embodiment of the present disclosure has been described, a method of engaging and disengaging the plunger 326 with respect to the piston 600 will now be described.

[0227] FIG. 18A shows the piston 600 with its plunger engagement mechanism 612 in the 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 600 by moving the piston 600 distally to allow insertion of one or more retaining members 368 of the plunger 326 into the receiving space 615 between the plunger engagement sleeve 614 and the plunger engagement post 618. In some embodiments, the piston 600 may be advanced distally using a drive mechanism 402 operated by a controller 200 (FIG. 2). In another embodiment, the piston 600 can be manually moved in the distal direction.

[0228] The piston 600 axially advances 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 at least one retaining member 368 is radially deflected inwardly by contact between the catch 374 and the inclined portion 630. In embodiments having a plurality of retaining members 368, each of the retaining members 368 is radially deflected inwardly. In some embodiments, there may be guide surfaces on both sides of the tapered end face 678 to assist rotation of the plunger engagement post 618 into the correct orientation for automatic alignment with the retaining member 368 of the plunger 326.

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

[0230] Distal movement of plunger engagement post 618 from the disengaged state or position to the engaged state or position closes receiving space 615 between plunger engagement sleeve 614 and plunger engagement post 618 to prevent removal of one or more retaining members 368 of plunger 326 from receiving space 615. When plunger engagement post 618 moves to the engaged position or state, catch 374 of at least one retaining member 368 of plunger 326 is captured between plunger engagement sleeve 614 and outer surface 667 of plunger engagement post 418 proximal to locking rib 634. Piston 600 and connected plunger 326 can then reciprocate within barrel 318 of syringe 300. In some embodiments, piston 600 can advance distally to deliver fluid from syringe 300 or proximally to fill syringe 300 with fluid using drive mechanism 402 operated by 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. Alignment of one or more release tabs 380 on the plunger 326 with the toothed portion 644 on the plunger engagement sleeve 614 also rotates the plunger engagement sleeve as the plunger 326 rotates. Since the plunger engagement post 618 is connected to the plunger engagement sleeve 614 via the rotation mechanism 671, the plunger engagement post 618 does not rotate with the rotation of the plunger engagement sleeve 614. In this way, the retaining member 368 of the plunger 326 slides within 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 one or more retaining members 368 of the plunger 326 from the receiving space 615 by a flexible distal displacement of at least one catch 374 of the retaining member 368 above the locking rib 634. To remove the plunger 326 from the piston 600, the syringe 300 can be pulled in the distal direction or the plunger 326 can be retracted in the proximal direction. During such relative movement of the piston 600 relative to the plunger 326 in a direction away from each other, the catch 374 is deflected above the locking rib 634 of the piston engagement sleeve 614 to permit removal of one or more retaining members 368 from the piston 600.

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

[0234] Referring initially to FIG. 19, a piston 700 and a plunger engagement mechanism 712 are shown in combination with a syringe port 16 of a syringe, such as syringe 10 shown in FIG. 1. The piston 700 is movable back and forth within the syringe port 16 in the direction of the longitudinal piston axis 720 via a drive mechanism 402, such as that shown in FIG. 2.

[0235] Referring to FIG. 20, an exploded view of the piston 700 and the plunger engagement mechanism 712 is shown. The piston 700 has a body 704 and a piston head 706 at the distal end of the body 704. The piston head 706 is configured to be removably connected to a plunger of a syringe, such as plunger 326 shown in FIGS. 7-8B. The plunger engagement mechanism 712 is integrated with the piston head 706. In some embodiments, at least a portion of the piston head 706 and / or the plunger engagement mechanism 712 may be made of a transparent or translucent material configured to allow passage of light emitted by one or more lights within the piston 700 to illuminate at least a portion of the plunger 326 and / or the syringe 300.

[0236] Continuing to refer to FIG. 20, piston 700 has sensing members 705 such as pin 707 and sensor 709. Pin 707 has a proximal end 713 configured to contact sensor 709 when the distal end 715 of pin 707 is forced in the proximal direction, such as by contact between plunger 326 and the distal end 715 of pin 707. Pin 707 can extend along the longitudinal axis 720 of piston 700 and can project through at least a portion of piston head 706. Pin 707 operates to sense contact with a surface such as the surface of plunger 326 and can transmit one or more signals to controller 200 (FIG. 2) to control movement of piston 700 based on the sensed conditions. For example, the first contact between distal end 715 of pin 707 and plunger 326 can move pin 707 in the proximal direction so as to contact sensor 709. Sensor 709 may be operatively connected to controller 200 such that when sensor 709 is actuated by pin 707, sensor 709 controls movement of the drive mechanism of piston 700. For example, the drive mechanism may be stopped or decelerated from a first speed to a second slower speed and to distal end 715 of pin 707 and plunger 326. Pin 707 may be biased to its distal position by spring 711.

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

[0238] Continuing to refer to FIG. 20, the plunger engagement post 718 has a post portion 721 that extends 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 at least one retaining member 368 of the plunger 326. The post portion 721 may be shaped to deflect at least one retaining member 368 radially outwardly by contact of the catch 374 with the outer surface of the post portion 721 and / or the locking lip 729. In this way, distal movement of the piston 700 relative to the plunger 326 deflects at least one retaining member 368 radially outwardly by contact between the catch 374 and the post portion 721. In embodiments having a plurality of retaining members 368, each of the retaining members 368 is deflected radially outwardly.

[0239] Continuing to refer to FIG. 20, the plunger engagement sleeve 714 has a hollow body 724, and at least a portion of the outer surface of the hollow body 724 defines at least a portion of the piston head 706. The distal portion or end 726 of the plunger engagement sleeve 714 is shaped to be received within an internal cavity 340 (shown in FIG. 21A) of the plunger 326, while at least a portion of the plunger 326, such as at least one retaining member 368, is configured to be received within a central opening 716. The central opening 716 extends through the hollow body 724 of the plunger engagement sleeve 714.

[0240] A portion of the inner surface 728 of the central opening 716 at the 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 engagement sleeve 714 to the proximal end of the plunger engagement sleeve 714. For example, the opening 716 may have a first step portion 717 having a first inner diameter and a second step portion 719 disposed proximal to the first step portion 717 and having a second diameter smaller than the first diameter of the first step portion 717. An inclined portion 730 may be provided between the first and second step portions 717, 719 to deflect at least one retaining 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 engagement sleeve 714.

[0241] Although the structure of the plunger 326 (see the disclosure of this specification with reference to FIGS. 6 to 8C) and the piston 700 according to a non-limiting embodiment of the present disclosure has been described, here, the method of engaging and disengaging the plunger 326 with respect to the piston 700 will be described with reference to FIGS. 21A to 21B. A part of the syringe 300 is shown in FIGS. 21A to 21B.

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

[0243] When the piston 700 can move distally, the catch 374 on at least one retaining member 368 of the plunger 326 is deflected radially outwardly 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 the distal direction relative to the plunger engagement sleeve 714 such that the retaining member 368 can be deflected radially outwardly within the space defined by the first step portion 717. After the catch 374 is disposed proximally relative to the locking lip 729, the at least one retaining member 368 can be elastically deflected in the radially inward direction, for example, by the elastic flexibility of the retaining member 368 in combination with the inclined portion 730 between the first and second step portions 717, 719. While the at least one retaining member 368 is in the position shown in FIG. 21A, as described herein, the at least one retaining member 368 can be flexibly deflected radially outwardly with the proximal movement of the piston 700 or the distal movement of the plunger 326 (such as by removal of the syringe from the injector), so the plunger 326 is not in locking engagement with the piston 700.

[0244] Referring to FIG. 21B, the plunger engagement post 718 moves from the disengaged position or state to the engaged position or state by moving proximally along the longitudinal piston axis 720. Such movement of the plunger engagement post 718 may be due to the actuator interrupting energy and allowing an elastic member, such as the elastic member 484 described herein with reference to FIGS. 9-13J, to axially force the plunger engagement post 718 proximally, or by applying energy to the actuator to move the plunger engagement post 718 proximally. The proximal movement of the plunger engagement post 718 locks at least one retaining member 368 and catch 374 within a space defined by the second stage 719 of the plunger engagement sleeve 714. Due to the smaller second diameter of the second stage 719 combined with the increased diameter of the locking lip 729, one or more retaining members 368 of the plunger 326 are captured within the receiving space 715 between the plunger engagement sleeve 714 and the plunger engagement post 718 such that 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 the disengaged position via axial movement of the plunger engagement post 718 distally, moving the locking lip 729 distally and allowing the catch 374 of one or more retaining members 368 to move around the locking lip 729 of the first stage 717, enabling removal of 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] Referring to FIGS. 22A-22E, a piston 800 and a plunger engagement mechanism 812 according to another embodiment of the present disclosure are shown. The components of the piston 800 and the plunger engagement mechanism 812 shown in FIGS. 22A-22E are substantially similar or identical to the components of the piston 400 and the plunger engagement mechanism 412 described herein with reference to FIGS. 9-13J. Accordingly, the reference numerals of FIGS. 22A-22E are used to denote the same components as the corresponding reference numerals of FIGS. 9-13J, except that the leading digit of the reference numerals used in FIGS. 22A-22E has been changed from "4" to "8". Since the foregoing description regarding the piston 400 and the plunger engagement mechanism 412 shown generally in FIGS. 9-13J is applicable to the piston 800 and the plunger engagement mechanism 812 shown in FIGS. 22A-22E, only the relative differences between the components shown in these figures are described below.

[0246] Referring to FIG. 22A, the piston 800 has a body 804 and a piston head 806 at the distal end of the body 804. The piston head 806 is configured to be removably connected to a plunger of a syringe, such as the plunger 326 shown in FIG. 8C. The plunger engagement mechanism 812 is integrated with the piston head 806. In some embodiments, at least a portion of the piston head 806 and / or the plunger 326 may be made of a transparent or translucent material configured to allow the passage of light emitted by one or more lights 803 within the piston 800 to illuminate at least a portion of the plunger 326 and / or the syringe 300.

[0247] The piston 800 has sensing members 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 the longitudinal axis 820 of the piston 800 and may be recessed within the piston head 806. The sensing sleeve 807 can operate to sense contact with a surface such as the surface of the plunger 326, and the controller 200 can be signaled to control the 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. The first contact between the distal end 815 of the sensing sleeve 807 and one or more retaining members 368 of the plunger 326 can cause the sensing sleeve 807 to be retracted proximally such that the sensing sleeve 807 actuates the sensor 809. The sensor 809 may be operably connected to the controller 200 and the drive mechanism of the piston 800 such that when the sensor 809 is actuated by the sensing sleeve 807, the sensor 809 signals the controller 200 to control the movement of the drive mechanism. For example, the drive mechanism may be stopped or decelerated 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 has 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 longitudinal piston axis 820 with respect to the plunger engagement sleeve 814 by the actuation of an actuator, such as actuator 422, described herein with reference to FIGS. 9 - 13J. In some embodiments, the plunger engagement post 818 is axially movable between an engaged position where the plunger 326 is latched in engagement with the piston 800 by capturing a catch 374 of at least one retaining member 368 of the locking rib 834 of the plunger engagement sleeve 814 and of the plunger 326 below the plunger engagement post 818, and a disengaged position where the plunger 326 can be removed from the piston 800.

[0249] The plunger engagement sleeve 814 has a hollow body 824, and at least a portion of the outer surface of the hollow body 824 defines at least a portion of the piston head 806. The distal portion or end 826 of the plunger engagement sleeve 814 is shaped to be received within the internal cavity 340 of the plunger 326, while at least a portion of the plunger 326, such as at least one retaining member 368, is configured to be received within the central opening 816. The central opening 816 extends through the hollow body 824 of the plunger engagement sleeve 814.

[0250] The inner surface of the central opening 816 has a locking rib 834 that projects radially inwardly from the inner surface 828. The locking rib 834 is configured to radially inwardly deflect at least one retaining member 368 associated with the plunger 326 during connection of the plunger 326 to the 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 at least one catch 374 on 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 in locking engagement with the plunger engagement mechanism 812 as described herein.

[0251] Although the structure of the plunger 326 and the piston 800 according to a non-limiting embodiment of the present disclosure has been described, the method of engaging and disengaging the plunger 326 with respect to the piston 800 will now be described with reference to FIGS. 22A-22E.

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

[0253] When moving from FIG. 22A to FIG. 22B, as the piston 800 advances toward the plunger 326, 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. A catch 374 on at least one retaining member 368 of the plunger 326 is deflected radially inwardly by contact with a locking rib 834 on the plunger engagement sleeve 814. The plunger engagement post 818 is in its disengaged position, for example, retracted in the proximal direction. While at least one retaining member 368 is in the position shown in FIG. 22B, the at least one retaining member 368 can be flexibly deflected radially inwardly with the proximal movement of the piston 800 or the distal movement of the plunger 326 (such as by removal of the syringe from the injector), so the plunger 326 is not in locking engagement with the piston 800.

[0254] Referring to FIG. 22C, when the sensing sleeve 807 moves proximally by contact with at least one retaining member 368 of the plunger 326, the sensor 809 detects the presence of the sensing sleeve 807 and actuates the actuator 822 to axially move the plunger engagement post 818 distally from its disengaged position or state to its engaged position or state. Such movement of the plunger engagement post 718 can result from interrupting the energy to the actuator 822. In another embodiment, the movement of the plunger engagement post 818 can result from applying energy to an actuator 822, such as a solenoid, or by operation of a motor for moving the actuator.

[0255] The movement of the plunger engagement post 818 from the disengaged state or position to the engaged state or position causes the receiving space 815 between the plunger engagement sleeve 814 proximal to the locking rib 834 and the plunger engagement post 818 to close to prevent removal of the catch 374 of one or more retaining members 368 of the plunger 326 from the receiving space 815. When the plunger engagement post 818 moves to the engaged position or state, the catch 374 of 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 the 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] Referring to FIG. 22D, to unlock the plunger 326 from the plunger engagement mechanism 812, the plunger engagement post 818 is moved to the disengaged position via axial movement in the distal direction, for example, by an actuator (described herein) or a stored restoring force from a biasing member, allowing removal of one or more retaining 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 in the distal direction by a restoring force provided by the spring 817 (FIG. 22E).

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

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

[0259] The piston 900 is extendable and retractable from the housing of the fluid injectors 10, 100 (Figs. 1 and 3). The piston 900 includes a stem 901 and a piston head 920 formed at the distal end of the stem 901. In certain embodiments, the piston head 920 may extend radially outwardly beyond the radial edge of the stem 901. The piston head 920 may have 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 to the piston 900. The piston cavity 940 can have at least one locking lip 950 projecting radially inwardly from the 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 continuous or discontinuous circumferentially around the piston cavity 940.

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

[0261] Referring to FIGS. 23A - 23G, piston 900 has a locking member 980 configured to lock plunger 326 against 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 so as to at least partially extend into piston cavity 940. When extended in the second position, the locking member 980 is inserted into cavity 340 of plunger 326 to prevent deflection of at least one retaining member 368 in the radially inward direction. For example, in the second engagement position, the locking member 980 holds the release surface 369 of the plunger 326 against the proximal surface 970 of the piston 900 so that the catch 374 cannot move beyond at least one locking lip 950, thereby locking the catch 374 against 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 a surface of the plunger 326, and the movement of the piston 900 may be controlled based on the detected condition.

[0262] The structure of plunger 326 and piston 900 according to a non - limiting embodiment has been described. Here, with reference to FIGS. 23A - 23G, the engagement and disengagement of plunger 326 with respect to piston 900 will be described. Syringe 12 shown in FIG. 23A is omitted from the remainder of FIGS. 23B - 23G 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 the pressure jacket 15 (FIG. 3). When the syringe 12 is inserted into the syringe port 16, various locking mechanisms (not shown) may be used to hold 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 can then advance distally toward the plunger 326 for engagement of the piston head 920 with the plunger 326.

[0264] Referring to FIGS. 23A-23B, the piston 900 advances axially in the distal direction (arrow A in FIGS. 23A-23B) such that the sloped distal surface 960 of the piston head 920 contacts at least one retaining member 368 of the plunger 326. Initially, the sloped distal surface 960 contacts a catch 374, such as a catch surface 375 of at least one retaining member 368. Since the catch 374 projects radially outwardly 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 proximal piston cavity 940 of the sloped distal surface 960. In this way, continued distal movement of the piston 900 deflects at least one retaining member 368 radially inwardly in a flexible and elastic manner by contact of the catch surface 375 of the plunger 326 with the distal surface 960 of the piston 900 (FIG. 23B). In an example having a plurality of retaining members 368, each of the retaining members 368 is deflected radially inwardly relative to the plunger longitudinal axis 334.

[0265] Referring to FIG. 23C, during the continuous axial movement of the piston 900 in the distal direction, the catch 374 axially advances beyond at least one lip 950 of the piston head 920. Due to the restoring force generated during the radial deflection of the at least one flexible retaining member 368, the catch 374 is snap - locked radially outwardly into a recess 990 disposed proximal to the at least one locking lip 950 (FIG. 23A). Thus, the plunger 326 is releasably held 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 arranged 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 deflect inwardly flexibly to disengage. The locking member 980 prevents the retaining member 368 from moving in the radially inward direction, thereby preventing the plunger 326 from being disengaged from the piston 900. In this way, the piston 900 can move in the proximal or distal direction, resulting in a corresponding movement of the plunger 326. The locking member 980 can be moved between a disengaged position and an engaged position by an electromechanical actuator such as a solenoid actuator, a rotary motor, or a linear motor. As shown in FIGS. 23A - 23B, the locking member 980 can reciprocate using a rotary motor to rotate the meshing surfaces of a screw - driven part with screw grooves.

[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 in the distal direction (arrow D in FIG. 23G) through the syringe 12 and / or moving the piston 900 in the proximal direction. Such relative movement between the piston 900 and the plunger 326 engages the inclined release surface 369 of the holding member 368 with the inclined proximal surface 970 of the piston 900. Continued movement of the plunger 326 away from the piston 900 deflects the holding member 368 radially inward to remove the lip 950. After removing the lip 950, the holding member 368 rebounds radially outward, thereby completely disengaging the plunger 326 from the piston 900.

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

[0268] Referring to FIG. 24B, the plunger engagement mechanism 1012 has a plunger engagement sleeve 1014 having a central opening 1016 and a plunger engagement post 1018 that is 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 retaining 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 disposed 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] Referring to FIG. 24B, the plunger engagement sleeve 1014 has a hollow body 1024, and at least a portion of the outer surface of the hollow body 1024 defines at least a portion of the piston head 1006. The distal portion or end 1026 of the plunger engagement sleeve 1014 is shaped to be received within the internal cavity 340 of the plunger 326, while at least a portion of the plunger 326, such as at least one retaining member 368, is configured to be received within the central opening 1016. The central opening 1016 extends through the hollow body 1024 of the plunger engagement sleeve 1014. The outer surface 1042 of the plunger engagement 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 engagement sleeve 1014 further includes at least one locking groove 1065 recessed in the inner surface of the central opening 1016. In some embodiments, at least one groove 1065 may be configured to receive a catch 374 of at least one retaining member 368 of the plunger 326 when the plunger 326 is connected to the plunger engagement 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 face 1078 configured to contact at least one retaining member 368 on the plunger 326 to flexibly deflect at least one retaining member 368 of the plunger 326 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 a catch 374 of 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 FIGS. 9 - 13J, to move the plunger engagement post 1018 relative to the plunger engagement sleeve 1014 between the engaged or latched position and the disengaged or unlatched position.

[0272] Referring to FIG. 24C, the proximal end 1074 of the shaft 1072 is received within 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 clockwise or counterclockwise about the longitudinal piston axis 1020, as described in accordance with various embodiments herein. For example, the rotation mechanism 1071 may be a one - way clutch.

[0273] Although the structure of the plunger 326 and the piston 1000 according to a non-limiting embodiment of the present disclosure has been described, the method of engaging and disengaging the plunger 326 with respect to the piston 1000 will be described here.

[0274] FIG. 24C shows the piston 1000 in which the plunger engagement mechanism 1012 is 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 retaining 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 within the locking groove 1065. In some embodiments, the piston 1000 may be advanced distally using a drive mechanism 402 operated by a controller 200 (FIG. 2). In another embodiment, the piston 1000 can be manually moved in the distal direction.

[0275] The piston 1000 axially advances 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 engagement sleeve 1014 such that at least one retaining member 368 is radially inwardly deflected by contact between the catch 374 and the inner surface of the plunger engagement sleeve 1014. In embodiments having a plurality of retaining members 368, each of the retaining members 368 is radially inwardly deflected.

[0276] During continuous axial movement of the piston 1000 in the distal direction, the catch 374 is radially outwardly deflected into the locking groove 1065 of the piston engagement sleeve 1014. After the catch 374 is disposed within the locking groove 1065, the 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 the 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 the disengaged state or position to the 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 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 state, 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 the 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 a controller 200 (Figure 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. Alignment of the toothed portion 329 on the plunger 326 with the toothed portion 1044 on the plunger engagement sleeve 1014 also causes rotation of the plunger engagement sleeve 1014 as the plunger 326 rotates. Since the plunger engagement post 1018 is connected to the plunger engagement sleeve 1014 via the 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] Figures 25A and 25B illustrate an embodiment of a piston - plunger engagement system according to another embodiment. Figure 25A shows the system in a disengaged position where the plunger comprises a radially inwardly facing mating flange or catch 2774 that extends proximally from the inner surface of the plunger base. The piston includes at least one flexible retaining member 2750 having at least one retaining catch 2755 configured to engage a corresponding mating flange or catch 2774 of the plunger base. In the disengaged position, the movable locking member 2798 is in a distal first position where the locking member 2798 is configured such that it does not engage at least one flexible retaining member 2750 of the piston 2700. As shown in Figure 25B, the piston - plunger engagement system is in an engaged position and the movable locking member 2798 is moved in the proximal direction, for example, by a motor, solenoid, or cam system. As the locking member 2798 moves proximally, the proximal face 2799, for example, the inclined face shown in Figures 25A and 25B, contacts and engages at least one flexible retaining member 2750 that bends the retaining member 2750 in a radially outward direction. As the retaining member 2750 moves radially outward, at least one retaining catch 2755 engages at least one radially inwardly facing mating flange or catch 2774 and locks the plunger base to the piston. Generally, at least one radially inwardly facing mating flange or catch 2774 is substantially non - flexible, for example, by the structural strength or outer surface of the plunger engagement sleeve 2714 that prevents the mating flange or catch 2774 from bending radially outward and being removed from at least one retaining catch 2755 of at least one flexible retaining member 2750. Moving the locking member 2798 in the distal direction releases the force applied to at least one flexible retaining member 2750 and allows the retaining member 2750 to return to its non - bent disengaged position, and at least one retaining catch 2755 does not contact or engage at least one radially inwardly facing mating 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 the disengaged position or the engaged position. For example, the resilient elastic member 2784 may be a compression spring configured to bias the locking member 2798 in the distal direction toward the disengaged position. In this way, the locking member 2798 is normally in the disengaged state so that the plunger can be disengaged from the locking member 2798 in the event of power loss. In another embodiment, the resilient elastic member 2784 may be a tension spring configured to bias the locking member 2798 in the proximal direction toward the engaged position. In such an embodiment, the locking member 2798 is normally in the engaged position, and an actuator 422 or the like described herein with reference to FIG. 9 is used to move it to the disengaged position in order 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 to be used with the injectors 10, 100 shown in FIGS. 1 and 3. In another embodiment, the piston 1100 may be configured to be used with any fluid injector configured for medical use, such as injection of a contrast agent and saline in a contrast imaging procedure. The piston 1100 is configured to reciprocate within the housing of the injector via a drive mechanism. The drive mechanism can 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 the 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 inner 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 of a transparent or translucent material configured to allow passage of light emitted by one or more lights within the piston 1100 to illuminate at least a portion of the plunger 326 and / or the syringe 300.

[0283] The piston head 1106 has a plunger engagement mechanism 1112 configured to releasably engage with the plunger 326 to facilitate reciprocating drive of the plunger 326 within the barrel of the syringe 300 and to facilitate rapid removal of the syringe 300 and the plunger 326 from the piston head 1106 and the fluid injector at the end of the 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 the 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 the engaged position or state, the plunger engagement post 1118 may be disposed 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 the disengaged position or state, the plunger engagement post 1118 may be disposed relative to the plunger engagement sleeve 1114 to permit removal of 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 can 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 automatically move to the disengaged state, such as during a power loss to the actuator 1122. In some embodiments, the actuator 1122 can be in the engaged state only during the proximal movement of the piston 1100. In some embodiments, the actuator 1122 may be a solenoid configured to be primarily in the disengaged state and may be in the engaged state only during the 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 backdriven in the event of a power loss to the injector. In various embodiments, moving one of the plunger engagement sleeve 1118 and the plunger engagement post 1118 to the disengaged state for removal of the plunger 326 from the piston 1100 may be achieved by rotation of the plunger 326 relative to the piston 1100, as described herein.

[0285] Referring to FIG. 27A, a plunger engagement sleeve 1114 according to one embodiment is described. The plunger engagement sleeve 1114 has a hollow body 1124, and at least a part of the outer surface of the hollow body 1124 defines at least a part of the piston head 1106 (FIG. 26). In some embodiments, the distal portion or end 1126 of the hollow body 1124 may have a conical shape configured to correspond to the shape of the internal cavity 340 of the conical portion of the plunger 326. At least a part 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 engagement sleeve 1114. The 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 attachment and detachment of the plunger 326 from the plunger engagement mechanism 1112, as described herein. The toothed portion 1144 has one or more plunger release teeth 1145 projecting from the outer surface 1142. The one or more plunger release teeth 1145 may project radially outward from the outer surface 1142 of the hollow body 1124. The one or more plunger release teeth 1145 are separated from each other by portions of the outer surface 1142 of the hollow body 1124 such that a groove is 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 each other. In some embodiments, the plunger release teeth 1145 may have a non-uniform angular spread and / or non-uniform angular spacing. The radial spacing of the plunger release teeth 1145 may be selected to correspond to the spacing between one or more release tabs 380 on the plunger 326. Each distal end 1147 of the plunger release teeth 1145 can have a tip 1149 configured to self-align and guide 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 one or more release tabs 380 on the plunger 326 to cause release of the plunger 326 from the piston during rotation of the plunger 326 about its longitudinal axis 334, such as by rotation of the syringe 300.

[0287] Referring to FIG. 27B, a portion of the inner surface 1128 of the central opening 1116 at the distal end of the opening 1116 can have an inclined portion 1130 such that the inner diameter of the opening 1116 tapers in a direction from the distal end 1126 of the hollow body 1124 towards the proximal portion or end 1132. In some embodiments, the inclined portion 1130 may be configured to deflect at least a portion of at least one retaining member 368 associated with the plunger 326 in a radially inward direction during connection of the plunger 326 to the distal portion or end 1126 of the plunger engagement sleeve 1114. In another embodiment, the inclined portion 1130 may define a clearance space for at least a portion of at least one retaining member 368, such as the catch 374, during connection of the plunger 326 to the plunger engagement 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 towards the proximal end of the plunger engagement sleeve 1114. For example, the opening 1116 may have a first inner diameter proximal to the inclined portion 1130 and a second diameter that is smaller than the first diameter distal to the inclined portion 1130. The inner surface 1128 of the central opening 1116 may be substantially cylindrical proximal to the inclined portion 1130. In another embodiment, one or both portions of the inner surface 1128 before and after the inclined portion 1130 may have a slight gradient inclined in the same direction as the inclined portion 1130.

[0288] Referring to FIGS. 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 side wall 1160 through which an opening 1162 passes. The opening 1162 can have a longitudinal plane 1163 that is substantially parallel to the longitudinal axis 1164 of the plunger release sleeve 1158, and an inclined plane 1166 that is adjacent to the longitudinal plane 1163 and is inclined with respect to the longitudinal axis 1164 of the plunger release sleeve 1158 in a direction from the distal end 1168 to the proximal end 1170. As described herein, the longitudinal plane 1163 is configured to guide the guide pin 1139 associated with the plunger engagement post 1118 during the longitudinal movement of the plunger engagement post 1118 along the longitudinal axis 1120 of the piston 1100, while the inclined plane 1164 is configured to guide the guide pin 1139 to move the plunger engagement post 1118 during the rotational movement of the plunger 326 with respect to the piston 1100, such as during the removal of the plunger 326 from the piston 1100.

[0289] Referring to FIG. 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 an outer diameter smaller than that of 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 the proximal end of a biasing member 1196 configured to release the plunger 326 from the plunger 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] Referring to FIG. 26, the plunger engagement sleeve 1114 and the plunger release sleeve 1158 are fixed so as not to rotate relative to each other, but as described herein with reference to FIGS. 30A-30D, both are rotatable about the longitudinal piston axis 1120 relative to the plunger engagement post 1118 between the first position and the second position. In some embodiments, the plunger engagement sleeve 1114 and the plunger release sleeve 1158 may be rotatable in the clockwise and counterclockwise directions, or in one of the clockwise and counterclockwise directions. The plunger engagement sleeve 1114 and the plunger release sleeve 1158 may be rotatable from the first position to the second position by the 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 by the interaction of the release tab 380 on the plunger 326 with the 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 to the first position. In this way, when 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, which is then used to assist in returning the plunger engagement sleeve 1114 and the plunger release sleeve 1158 to the first position.

[0291] Referring to FIG. 29, the plunger engagement post 1118 is shown separately from the plunger engagement mechanism 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 deflect at least one retaining member 368 radially outwardly 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 at least one retaining member 368 of the plunger 326. The end face 1178 may be shaped to deflect at least one retaining member 368 radially outwardly by contact of the catch 374 with the outer surface of the end face 1178. In this way, distal movement of the piston 1100 relative to the plunger 326 deflects at least one retaining member 368 radially outwardly by contact between the catch 374 and the rounded or tapered outer surface of the end face 1178.

[0294] The plunger engagement post 1118 has sensing members 1105 such as pin 1107 and 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 in the proximal direction, such as by contact between the plunger 326 and the distal end 1117 of the pin 1107. The pin 1107 can extend along the longitudinal axis 1120 of the piston 1100 and can protrude through at least a portion of the piston head 1106. The pin 1107 operates to detect contact with a surface such as the inner surface of the plunger 326 and can transmit one or more signals to the controller 200 of the fluid injector to control the movement of the piston 1100 based on the detected conditions. For example, the first contact between the distal end 1117 of the pin 1107 and the plunger 326 can cause the pin 1107 to retract in the proximal direction to activate the sensor 1109. The sensor 1109 may be operably connected to the controller 200 that controls the drive mechanism of the piston 1100 such that when the sensor 1109 is actuated by the pin 1107, the sensor 1109 controls the movement of the drive mechanism. For example, the drive mechanism may be stopped or decelerated 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 the entry of fluid.

[0295] Continuing to refer to FIG. 29, one or more lights 1173 may be provided on the 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] Although the structures of the plunger 326 and the piston 1100 according to a non-limiting embodiment of the present disclosure have been described, here, the method of engaging the plunger 326 with the piston 1100 will be described with reference to FIGS. 30A to 30D. FIGS. 31A to 31D show the plunger engagement mechanism 1112 at various stages of disengaging the plunger 326 from the piston 1100.

[0297] FIG. 30A shows the piston 1100 before the plunger engagement mechanism 1112 is in the disengaged position or state and before connecting to the plunger 326. In some embodiments, the default state of the plunger engagement mechanism 1112 may be the engaged position or state. In another embodiment, the default state of the plunger engagement mechanism 1112 may be the disengaged position or state. To connect the plunger 326 to the piston 1100, the syringe 300 is first connected to the injector. During the connection of the syringe 300 to the injector, the piston 1100 is drawn into the housing of the injector. After connecting the syringe 300 to the injector, the piston 1100 can advance distally towards the plunger 326 within the hole of the syringe 300.

[0298] Referring to FIG. 30A, the actuator 1122 (shown in FIG. 26) is operated to the disengaged position or state, and the plunger engagement post 1118 is disposed at its distal position. The 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 allow the insertion of one or more retaining members 368 of the plunger 326 into the receiving space 1115. The pin 1107 is at 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] Referring to FIG. 30B, piston 1100 is axially moved in a distal direction toward plunger 326 (shown by arrow A1). In some embodiments, piston 1100 may be advanced distally using a drive mechanism 402 operated by an injector controller 200 (FIG. 2). In another embodiment, the piston can be manually moved in the distal direction. Piston 1100 is advanced axially in the distal direction such that at least one retaining member 368 of plunger 326 is received within central opening 1116 of plunger engagement sleeve 1114. As piston 1100 advances distally toward plunger 326, at least a portion of one or more retaining members 368 on plunger 326 contacts tapered end face 1178 of plunger engagement post 1118, thereby flexibly deflecting retaining member 368 in a radially outward direction. For example, since catch 374 projects radially inwardly relative to the second end of retaining member 368, catch 374 contacts tapered surface 1178 of plunger engagement post 1118, thereby deflecting retaining member 368 in a radially outward direction. In embodiments having a plurality of retaining members 368, each of the retaining members 368 is deflected radially outwardly.

[0300] Referring to FIG. 30C, during continued axial movement of the piston 1100 in the distal direction, the retaining member 368 is positioned such that the catch 374 can deflect into the locking groove 1127 of the piston engagement post 1118. After the catch 374 is disposed within the locking groove 1127, at least one retaining member 368 can elastically deflect in a radially inward direction, and the retaining member 368 can climb the inclined portion 1130 of the inner surface 1128 of the central opening 1116 and enter the second diameter of the inner surface 1128. While at least one retaining member 368 is in the position shown in FIG. 30C, at least one retaining member 368 can be deflected radially outwardly with proximal movement of the piston 1100 or distal movement of the plunger 326 (such as by removal of the syringe from the injector), so that the plunger 326 is not in locking engagement with the piston 1100 and the catch 374 can exit the locking groove 1127. With the plunger 326 connected to the piston 1100, one or more release tabs 380 on the plunger 326 are aligned with the toothed portion 1144 on the outer surface 1142 of the plunger engagement sleeve 1114 (FIG. 30A). The pin 1107 of the sensing member 1105 moves axially in the proximal direction by 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] Referring to FIG. 30D, actuator 1122 (FIG. 26) is operative to move plunger engagement post 1118 in the proximal direction indicated by arrow B1 from a disengaged position or state to an engaged position or state. Movement of plunger engagement post 1118 in the distal direction closes receiving space 1115 between plunger engagement sleeve 1114 and plunger engagement post 1118, which locks catch 374 in locking groove 1127, to prevent one or more retaining members 368 of plunger 326 from disengaging and exiting receiving space 1115. When plunger engagement post 1118 moves to the engaged position or state, at least one retaining member 368 of plunger 326, including catch 374, is captured between plunger engagement sleeve 1114 and plunger engagement post 1118 such that axial movement of piston 1100 results in corresponding axial movement of plunger 326 within syringe barrel. When plunger engagement post 1118 moves in the proximal direction, guide pin 1139 moves axially in the distal direction from distal end 1151 to proximal end 1153 of longitudinal face 1163 of opening 1162 (FIG. 28) in plunger release sleeve 1158.

[0302] Piston 1100 and attached plunger 326 can then reciprocate within barrel 318 of syringe 300. In some embodiments, piston 1100 can be advanced distally to deliver fluid from syringe 300 or proximally to fill syringe 300 with fluid using drive mechanism 402 operated by controller 200 (FIG. 2).

[0303] Referring to FIGS. 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. Since there is substantially no rotation within the syringe barrel 318 due to the frictional contact therebetween, the rotation of the syringe 300 also rotates the plunger 326 relative to the piston 1100 about the longitudinal piston axis 1120. 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 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. The guide pin 1139 on the plunger engagement post 1118 is received in the opening 1162 on the plunger release sleeve 1158, and since the plunger engagement post 1118 does not rotate about the longitudinal piston axis 1120, the rotation of the plunger engagement sleeve 1114 guides the guide pin 439 along the inclined surface 1166 of the plunger release sleeve 1158 (see also FIG. 28) from the first position shown in FIG. 30D to the second position shown in FIG. 31A (e.g., from the proximal end of the inclined surface 1166 towards the distal end of the inclined surface 1166). Additionally, the rotation of the plunger engagement sleeve 1114 about the longitudinal piston axis 1120 builds potential energy within the biasing member 1196.

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

[0305] When the plunger engagement mechanism 1112 is in the disengaged position or state, the syringe 300 can be pulled in the distal direction to remove the plunger 326 from the piston 1100, or the piston 1100 can be retracted in the proximal direction. During such relative movement of the piston 1100 with respect to the plunger 326 in a direction away from each other, each catch 374 of at least one retaining member 368 engages with the plunger engagement post 1118 distal to the locking groove 1127 such that each retaining member 368 is flexibly deflected in the radially outward direction (FIG. 31C). Continued movement of the piston 1100 with respect to the plunger 326 allows the plunger 326 to be freely separated from the piston 1100, as shown in FIG. 31D, and allows removal of the syringe 300 from the injector port.

[0306] Referring to FIG. 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. Movement of the plunger engagement sleeve 1114 and the plunger engagement post 1118 to the first position guides the guide pin 1139 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] Next, referring to FIGS. 32-35B, an injector assembly 2000 according to another aspect 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, and each syringe may be independently filled with a medical fluid such as a contrast agent, saline, or any desired medical fluid as described above with respect to FIGS. 1 or 3. For example, the injector housing 2002 is configured to hold syringes 2006a, 2006b, each containing a medical fluid.

[0308] As is known in the art, syringes 2006a, 2006b are often made of polypropylene or similar materials with a specific minimum wall thickness. During certain procedures such as angiography procedures, syringes 2006a, 2006b can be subjected to pressures up to 1200 psi when used to inject fluid into a patient, and thus the thickness and elasticity of the syringe are important in ensuring that the syringe does not radially expand, rupture, disengage from the injector, or leak. To further counter the possible radial expansion of syringes 2006a, 2006b when subjected to high-pressure injection, respective pressure jackets 2004a, 2004b can be utilized to enclose and hold syringes 2006a, 2006b. Pressure jackets 2004a, 2004b act to limit the radial expansion of the syringe barrel. That is, during the injection procedure, the outer walls of syringes 2006a, 2006b expand against the inner walls of respective pressure jackets 2004a, 2004b, thereby limiting the radial expansion of the outer walls of the syringe that could otherwise lead to rupture or leakage.

[0309] Pressure jackets 2004a, 2004b may be separate elements or may be formed as an integral design of a component part. Pressure jackets 2004a, 2004b are held on the injector head of housing 2002 via respective mounting interfaces 2010a, 2010b. Suitable non-limiting examples of pressure jackets that include a syringe holding function for use in CV injection procedures are described in International Application No. US2020 / 049885, which is incorporated herein by reference.

[0310] In addition to the radial forces acting on syringes 2006a, 2006b and pressure jackets 2004a, 2004b, significant axial movement during high-pressure injection is also possible due to the elastic properties of the structural components that restrain syringes 2006a, 2006b. For example, at 1200 psi for 1.6 in 2A single 150 ml syringe having a cross-sectional area may require a force of 2400 psi to inhibit forward movement of the syringe. To limit this axial movement of syringes 2006a, 2006b, the distal ends of syringes 2006a, 2006b are partially enclosed, and respective caps 2008a, 2008b may be used to hold syringes 2006a, 2006b within the injector and within pressure jackets 2004a, 2004b during high-pressure injection. Caps 2008a, 2008b can have an opening formed at their distal ends to allow at least a portion of necks 2009a, 2009b of syringes 2006a, 2006b to project therethrough, thereby enabling syringes 2006a, 2006b to be connected to a fluid line connected to a patient.

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

[0312] To achieve these desirable characteristics, the attachment interfaces 2010a, 2010b of the pressure jackets 2004a, 2004b can have a connector functional portion similar to that of the plunger 326 illustrated and described with reference to FIGS. 6 to 8C, while the attachment interfaces 2020a, 2020b of the housing 2002 shown in FIG. 32 can have a connector functional portion similar to that of various embodiments of the plunger engagement mechanism illustrated and described with reference to FIGS. 9 to 31D. That is, the attachment interfaces 2010a, 2010b can include one or more elastic flexible retaining members having catches, similar to the elastic flexible retaining members 368 and catches 374 illustrated and described with reference to FIGS. 6 to 8C, which are circumferentially arranged around the openings at the proximal ends of the pressure jackets 2004a, 2004b. Similarly, the attachment interfaces 2020a, 2020b of the housing 2002 can include one or more functional portions similar to the plunger engagement sleeves and plunger engagement posts illustrated and described with reference to FIGS. 9 to 31D.

[0313] During operation, attachment interfaces 2010a, 2010b, and 2020a, 2020b are configured to interact in a manner substantially similar to the interaction between plunger 326 and the plunger engagement mechanism, as illustrated and described in detail with reference to FIGS. 9-31D. That is, since attachment interfaces 2010a, 2010b are axially oriented toward their respective attachment interfaces 2020a, 2020b, each of attachment interfaces 2010a, 2010b and attachment interfaces 2020a, 2020b interact to enable pressure jackets 2004a, 2004b to be secured to housing 2002. Then, in certain embodiments, one or more retention members within attachment interfaces 2020a, 2020b that can protrude from the distal ends of attachment interfaces 2020a, 2020b are configured to engage with the lips of the engagement rings within each of attachment interfaces 2010a, 2010b to securely attach pressure jackets 2004a, 2004b to housing 2002.

[0314] To separate pressure jackets 2004a, 2004b from housing 2002, pressure jackets 2004a, 2004b can be rotated (either together or separately) relative to housing 2002. Rotation of pressure jackets 2004a, 2004b enables attachment interfaces 2010a, 2010b to interact with attachment interfaces 2020a, 2020b in a manner similar to that described above with reference to FIGS. 9-31D. This interaction of the operation pushes at least one retention member radially outward or inward such that at least one retention member no longer engages the corresponding structure on attachment interfaces 2010a, 2010b, at which point pressure jackets 2004a, 2004b can be axially separated from housing 2002.

[0315] Alternatively, upon insertion, the proximal ends of the bodies of syringes 2006a, 2006b within pressure jackets 2004a, 2004b can act like the plunger engagement posts to lock the catch of the corresponding flexible retaining member of the pressure jacket to the corresponding locking groove or lip within the pressure jacket port of the injector. For example, removal of syringes 2006a, 2006b from pressure jackets 2004a, 2004b, such as after completion of an injection protocol, can disengage the flexible retaining member of the pressure jacket from the corresponding locking groove or lip within the pressure jacket port, enabling removal of the pressure jacket from the port.

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

[0317] Next, referring to FIGS. 34, 35A, and 35B, an alternative aspect of the present disclosure is shown. As described above with respect to FIGS. 32 - 33, caps 2008a, 2008b may generally be provided around the distal ends of respective pressure jackets 2004a, 2004b to axially retain the respective syringes. As shown in FIG. 35A, cap 2008 can have an attachment interface 2014 for attachment to the pressure jacket, as well as an opening 2016 formed to penetrate a portion of the distal end of the syringe.

[0318] To obtain a secure connection between the pressure jackets 2004a, 2004b and the caps 2008a, 2008b, the respective interfaces between the pressure jackets 2004a, 2004b and the caps 2008a, 2008b are configured to interact in substantially the same manner as the interaction between the various embodiments of the plunger 326 and the various embodiments of the plunger engagement mechanism illustrated and described in detail in FIGS. 9-31D. As shown in FIG. 33, the pressure jackets 2004a, 2004b can each 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 illustrated and described with respect to FIGS. 9-31D. Similarly, the attachment interface 2014 of the cap 2008 shown in FIG. 35A can include one or more elastically deflectable retaining members 368 together with a corresponding catch 374, as illustrated and described with reference to FIGS. 6-8C. The engagement between the attachment interfaces 2012a, 2012b of the pressure jackets 2004a, 2004b and the attachment interface 2014 of the respective caps 2008 can 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 way, the caps 2008a, 2008b can be securely engagable with the distal ends of the pressure jackets 2004a, 2004b and can be easily removable.

[0319] As an alternative to the cap 2008 that separates from and surrounds a portion of the syringe, FIG. 35B shows a syringe assembly 2030 having a syringe body 2032 with an integrated cap 2036. That is, the cap 2036 may be directly molded or formed together with the syringe body 2032. The neck portion 2034 extends from the distal face of the cap 2036 to provide a connection point to a fluid line leading to a patient. An attachment interface 2038 similar to the attachment interface 2014 illustrated and described with respect to FIG. 35A is formed within the cap 2036. As similarly described above with respect to FIGS. 32 and 35A, the attachment interface 2038 can include functional portions that interact with one of the corresponding attachment interfaces 2012a, 2012a of the pressure jackets 2004a, 2004b. Again, the engagement between the attachment interfaces 2012a, 2012b of the pressure jackets 2004a, 2004b and the attachment interface 2038 of each syringe assembly 2030 may be the same as or substantially similar to that described above with respect to FIGS. 9 - 31D.

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

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

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

Description of the Reference Numerals

[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 and 19B Bulk Fluid Containers Proximal ends of 20, 320, 336, 382, 432, 470, 474, 490, 532, 632, 674, 713, 813, 1074, 1113, 1132, 1153, 1176 21A and 21B Bulk Fluid Paths 23A and 23B Bulk Fluid Valves Plungers of 26, 326 100 Dual Syringe Angiography Injector System, Injector 200 Controller 202 Bus 204 Processor 206 Memory 208 Memory Component 210 Input Component 212 Output Component 214 Communication Interface 240 Upstream Air Detector 250 Air Detection Tube Region 315 Syringe Longitudinal Axis 318 Syringe Barrel 319 Side Wall Outer Surfaces of 321, 360, 442, 1042, 1142 322 Nozzle Inner Surfaces of 323, 352, 428, 436, 728, 828, 1128 Distal ends of 324, 338, 426, 468, 476, 478, 486, 626, 676, 726, 815, 826, 1076, 1117, 1147, 1151, 1174 325 Internal Volume 327 Drive Shoulder Toothed Parts of 329, 444, 544, 644, 1044, 1144 330 Insertion Section 331 Syringe Holding Member 332 Plunger Body 334 Plunger Longitudinal Axis 335 Drip Flange 339 Circumferential Side Wall 340 Internal Cavity 342 Conical-shaped part 344 Cylindrical-shaped part 345, 456, 679, 1156 Ledges 346 End portion 347a, 673 First portion 347b, 675 Second portion 348 Forming boss, surface 350 Retaining rib 356 Extension 357 Plunger cover 358 Elastic seal 362 Circumferential groove 364 Outer surface 368 Flexible retaining member 366 Sealing element 369, 369b Rounded or beveled 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 motor, drive mechanism 404, 704, 804, 1104 Body 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 Receiving space 416, 516, 616, 716, 816, 1016, 1116 Central opening 418 Plunger engagement post 420 Longitudinal piston axis, longitudinal axis 422, 822, 1122 Actuator 424 Actuator, hollow body Inclined portions 430, 530, 630, 730, 1130 Locking ribs 434, 634, 834 Longitudinal grooves 438, 538 Guide pins 439, 539, 1139 Distal stops 440, 540 Housings 446, 1146, 2002 Connecting member 448 Male screw connector 450 Proximal portions 452, 519 Distal portion 454 Plunger release sleeves 458, 558, 1158 Cylindrical side walls 460, 560, 1160 Openings 462, 523, 562, 1162, 2016 Longitudinal surfaces 463, 563, 1163 Longitudinal axis, inclined surface 464 Inclined surfaces 466, 566, 1166 Shaft, light 472 Printed circuit boards 474, 1175 Tapered end faces 478, 678, 1078 Seals 480, 1119, 1180 Longitudinal axes 482, 531, 564 Elastic elastic members 484, 2784 Ledges 488 Biasing members 496, 1196 Plunger engagement mechanisms 512, 612, 712, 812, 1012 Plunger engagement sleeves 514, 714, 814, 2714 Plunger engagement posts, piston engagement posts 518 Piston longitudinal axis, longitudinal piston axis, longitudinal axis 520 Post portions 521, 721 Hollow bodies 524, 624, 724, 824, 1024, 1124 Connection pieces 525 Distal end, end 526 Locking grooves 527, 1127 Inner surface 528 533 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 member 707, 1107 Pin 709, 809, 1109 Sensor 711 Spring 715 Distal end, receiving space 717 First step portion 719 Second step portion 720 Longitudinal axis, longitudinal piston axis 722 Actuator 723 Proximal portion 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 inclined distal surface 970 Rounded or inclined 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 teeth 1149 Tip 1152 Proximal portion 1154 Distal portion 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 portion 2750 Flexible holding member 2755 Holding catch 2774 Engagement flange or catch 2798 Movable locking member

Claims

1. A fluid injector system comprising: at least one reciprocating piston having a piston head; and a plunger engagement mechanism associated with the piston head and configured to engage the plunger of the syringe connected to the fluid injector system to reciprocally drive 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; a plunger engagement post receivable within the hollow body of the plunger engagement sleeve; an actuator operably connected to one of the plunger engagement sleeve and the plunger engagement post and configured to move one of the plunger engagement sleeve and the plunger engagement post between an engaged position and a disengaged position; a plunger engagement mechanism comprising the above; and comprising: at the engaged position, the plunger engagement post is disposed within the 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 sleeve and the plunger engagement post; at the disengaged position, the plunger engagement post is 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 retaining member of the plunger from the receiving space. A fluid injector system.

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

3. The fluid injector system according to claim 1, wherein the actuator is manually operated.

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

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

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

7. The fluid injector system according to claim 1, wherein the rotational movement of the actuator moves one of the plunger engagement sleeve and the plunger engagement post proximally or distally in a linear direction.

8. The fluid injector system according to claim 1, wherein the linear movement of the actuator moves one of the plunger engagement sleeve and the plunger engagement post proximally or distally in a linear direction.

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

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

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

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

13. The distal edge of the locking groove is configured to flexibly deflect the at least one retaining member of the plunger during axial movement of the plunger relative to the piston to move the at least one catch out of engagement with the locking groove when one of the plunger engagement sleeve and the plunger engagement post is moved to the disengaged position. The fluid injector system according to claim 12.

14. The plunger has a plunger body defining a central longitudinal axis and having a proximal end, a distal end, and a circumferential sidewall connecting the proximal end and the distal end. at least one retaining member associated with the plunger body and extending proximally from the plunger body; The fluid injector system according to claim 1, comprising.

15. The at least one retaining member is a first end connected to the plunger body, a second end proximal to the first end and radially elastically deflectable relative to the first end, and at least one catch on the second end; comprising The at least one retaining member has an outer surface configured to engage the plunger engagement sleeve when the plunger is engaged with the piston. The at least one retaining member has an inner surface configured to engage the plunger engagement post when the plunger is engaged with the piston. The at least one catch is configured to fixedly engage with one of the locking functional parts of the plunger engagement sleeve and the plunger engagement post when the plunger is engaged with the piston, so as to prevent the axial movement of the plunger relative to the piston. In the unlocked state of the plunger engagement mechanism, the at least one catch is configured to radially deflect the second end of the at least one retaining member during the axial movement of the piston relative to the plunger by the flexible interaction of the at least one catch with the locking functional part. The fluid injector system according to claim 1.

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

17. The at least one catch of the fluid injector system according to claim 15 projects radially inwards from the inner surface of the at least one retaining member in a direction towards the central longitudinal axis.

18. The at least one catch of the fluid injector system according to claim 17 is configured to be received within the locking functional part formed as a locking groove projecting radially inwards from the outer surface of the plunger engagement post when the plunger is in the locked state with the piston.

19. The fluid injector system according to claim 15, wherein the 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.

20. The fluid injector system according to claim 19, wherein the at least one catch is configured to be received within a locking feature formed as a locking groove that projects radially outward from an inner surface of the plunger engagement sleeve.

21. The at least one catch a first rounded proximal surface at a proximal end of the at least one catch, wherein during engagement of the plunger to the piston, the at least one catch is configured to engage flexibly with a distal end of the locking feature of one of the plunger engagement sleeve and the plunger engagement post; and a second rounded distal surface at a distal end of the at least one catch, wherein during disengagement of the plunger from the piston, the at least one catch is configured to engage flexibly with a proximal end of the locking feature of one of the plunger engagement sleeve and the plunger engagement post; The fluid injector system according to claim 15, comprising.

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