Abstract:
A syringe interface is provided for attaching a syringe to an injector. The syringe includes, a first and second set of generally opposing, radially outward projecting mounting flanges, and a second set of flanges offset from the first set of mounting flanges. The syringe interface includes a first set of generally opposed slots adapted to receive therethrough the first set and second set, respectively, of mounting flanges, and a first and second set of generally opposed retaining flanges adapted to releasably engage the first and second set respectively, a set of mounting flanges, when the syringe is rotated within the syringe interface. The syringe verification mechanism includes at least one flange interaction element disposed within at least one slot of the first set of slots, and at least a first flange abutment member being positioned to prevent engagement of the second set of mounting flanges with the second set of retaining flanges unless the flange verification element interacts with at least one of the flanges of the first set of mounting flanges.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims benefit of U.S. Provisional Patent Application Ser. No. 60/552,962, filed Mar. 12, 2004, the disclosure of which is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   The present invention relates generally to syringe interfaces, syringe adapters and injectors and, more particularly, to syringe interfaces, syringe adapters and injectors for use in injection of a fluid into a patient. 
   Injector-actuated syringes and powered injectors are used in medical procedures such as angiography, computed tomography, ultrasound and NMR/MRI. U.S. Pat. No. 4,006,736, for example, discloses an injector and syringe for injecting fluid into the vascular system of a human being or an animal. Typically, such injectors comprise drive members such as pistons that connect to a syringe plunger. For example, U.S. Pat. No. 4,677,980, the disclosure of which is incorporated herein by reference, discloses an angiographic injector and syringe wherein the drive member of the injector can be connected to, or disconnected from, the syringe plunger at any point along the travel path of the plunger via a releasable mechanism. A front-loading syringe and injector system is also disclosed in U.S. Pat. No. 5,383,858, the disclosure of which is incorporated herein by reference. 
   The front-loading injector of U.S. Pat. No. 5,383,858 includes a bayonet syringe mounting mechanism for securing the syringe to the front wall of the injector. In that regard, the syringe of U.S. Pat. No. 5,383,858 includes two generally opposed mounting flanges on a rearward end of the syringe which cooperate with corresponding retaining flanges on the injector thereof to form a bayonet connection. 
   U.S. Pat. No. 5,873,861 discloses another front-loading, bayonet-type syringe mounting mechanism in which multiple pairs or sets of syringe mounting flanges cooperate with corresponding pairs of injector retaining flanges to mount a syringe upon an injector. In one embodiment, a first pair of mounting flanges are offset from at least a second pair of mounting flanges. For example, the first pair of mounting flanges can be offset from the second pair of mounting flanges by approximately 90°. Use of multiple pairs of mounting flanges and, particularly offset pairs of mounting flanges, can, for example, assist in distributing forces experienced by a syringe during an injection procedure. Such flange configurations can thereby allow use of certain syringe manufacturing materials at higher pressures than previously attainable or the use of relatively low-strength materials not otherwise usable with high pressure-syringe and injector designs without the use of a pressure jacket. 
   Other types of mounting mechanisms for front-loading syringes are disclosed in PCT Publication No. WO 01/37903 and U.S. Pat. No. 6,652,489, each assigned to the assignee of the present invention, the disclosures of which are incorporated herein by reference. 
   In general, the use of specifically designed mounting mechanisms on front-loading injectors prevents the use of syringes of various other types (that is, syringes having a mounting mechanism not directly compatible with the syringe interface/retaining mechanism of the front-loading injector) with the front-loading injectors. Syringe adapters attachable to front-loading injectors are sometimes used to allow the use of such syringes with front-loading injectors. 
   For example, U.S. Pat. No. 5,520,653 discloses several adapters designed to allow the use of various syringes with a front-loading injector. Another adapter for allowing use of various syringes with a front-loading injector is disclosed in Japanese Patent Publication No. 09-122234. Other adapters are disclosed, for example, in PCT Publication No. WO 01/08727 and U.S. patent application Ser. No. 09/633,299, filed on Aug. 8, 2000, each assigned to the assignee of the present invention, the disclosures of which are incorporated herein by reference. 
   Although a number of syringe interfaces and adapters are currently available, it remains desirable to develop improved syringe interfaces and adapters for use with syringes of various types. 
   SUMMARY OF THE INVENTION 
   A syringe interface is provided for attaching a first syringe to an injector. The first syringe includes a main body, a plunger movably disposed within the main body, a first set of generally opposing, radially outward projecting mounting flanges, and a second set of generally opposing, radially outward projecting mounting flanges, the first set of mounting flanges being offset from the second set of mounting flanges. The syringe interface includes a first set of generally opposed slots adapted to receive therethrough the first set of mounting flanges, a second set of generally opposed slots adapted to receive therethrough the second set of mounting flanges, the first set of slots being offset from the second set of slots, a first set of generally opposed retaining flanges adapted to releasably engage the first set of mounting flanges, a second set of generally opposed retaining flanges adapted to releasably engage the second set of mounting flanges when the syringe is rotated within the syringe interface to bring the first set of mounting flanges into general alignment with the first set of retaining flanges and the second set of mounting flanges into general alignment with the second set of retaining flanges, and a syringe verification mechanism. The syringe verification mechanism includes at least one flange interaction element disposed within at least one slot of the first set of slots, and at least a first flange abutment member in operative connection with the flange verification element, the first flange abutment member being positioned to prevent engagement of the second set of mounting flanges with the second set of retaining flanges unless the flange verification element interacts with at least one of the flanges of the first set of mounting flanges. 
   In one embodiment, the flange verification element includes a contact member that is movably disposed within at least one slot of the first set of slots. The contact member can, for example, be slidably disposed in an axial direction within the at least one slot and the first flange abutment member can be in mechanical connection with the contact member. 
   The first flange abutment member can include a first contact member slidably disposed in an axial direction within the at least one slot of the first set of slots. The syringe verification mechanism can further include a second contact member slidably disposed in an axial direction within the other slot of the first set of slots. The first contact member and the second contact member can, for example, project forward from an annular member that is slidably disposed within the syringe interface. The second contact member can be positioned with respect to the annular member generally opposite to the first contact member. 
   The syringe interface can further include a plunger abutment adapted to contact a plunger of a third syringe during attachment of the third syringe to the syringe interface. The syringe interface can also include a plunger interface slidably disposed within the plunger abutment. In one embodiment, the plunger abutment comprises a generally cylindrical member. The plunger interface can include at least two radially outward extending connection flanges on a forward end thereof that cooperate with at least two relatively flexible capture members protruding from the rear of the plunger. The flexible capture members flex when contacted by the connection flanges to form a connection with the plunger interface. 
   The piston interface can further include at least two sloped surfaces to the rear of the connecting flanges at an axial position in general alignment with the axial position of a radially inward projecting flange on the rearward end of each of the flexible capture members when the plunger is connected to the plunger interface. The radius of each of sloped surfaces can increase around the circumference thereof until the radius of each of the sloped surfaces is at least equal to the radius of one of the connecting flanges. In one embodiment, upon rotation of the plunger relative to the piston interface, the flexible capture members are flexed outwardly by contact of the radially inward extending flanges of the flexible capture member with the sloped surfaces until the radially inward extending flanges can pass forward of the connecting flanges of the piston interface, thereby enabling detachment of the plunger from the plunger interface. 
   In another aspect, the present invention provides an adapter for connecting a first syringe to an injector including an injector syringe interface adapted to connect a second to the injector. The first syringe includes an elongated main body, a plunger movably disposed within the main body, at least a first set of generally opposing, radially outward projecting mounting flanges, and at least a second set of generally opposing, radially outward projecting mounting flanges. The first set of mounting flanges is offset from the second set of mounting flanges. The adapter includes an injector interface adapted to connect the adapter to the injector syringe interface and a syringe interface adapted to connect the first syringe to the adaptor. The syringe interface includes a first set of generally opposed slots adapted to receive therethrough the first set of mounting flanges and a second set of generally opposed slots adapted to receive therethrough the second set of mounting flanges. The first set of slots are offset from the second set of slots. The syringe interface also includes a first set of generally opposed retaining flanges adapted to releasably engage the first set of mounting flanges and a second set of generally opposed retaining flanges adapted to releasably engage the second set of mounting flanges when the syringe is rotated within the syringe interface to bring the first set of mounting flanges into general alignment with the first set of retaining flanges and the second set of mounting flanges into general alignment with the second set of retaining flanges. The syringe interface further includes a syringe verification mechanism including at least one flange interaction element disposed within at least one slot of the first set of slots and at least a first flange abutment member in operative connection with the flange verification element. The first flange abutment member is positioned to prevent engagement of the second set of mounting flanges with the second set of retaining flanges unless the flange verification element interacts with at least one of the flanges of the first set of mounting flanges. 
   In a further aspect, the present invention provides an injector system including a first syringe including a main body; a plunger slidably disposed within the main body; a first set of generally opposing, radially outward projecting mounting flanges; and a second set of generally opposing, radially outward projecting mounting flanges. The first set of mounting flanges are offset from the second set of mounting flanges. The injector system also includes an injector including a drive member adapted to impart force to the syringe plunger and a syringe interface as described above adapted to connect the first syringe to the injector. 
   In another aspect, another embodiment of a syringe interface for attaching a first syringe to an injector is provided. The first syringe includes a main body, a plunger slidably disposed within the main body and a mounting mechanism associated with the main body. The syringe interface includes a retaining mechanism adapted to cooperate with the mounting mechanism of the first syringe, and a plunger abutment extending forward to a predetermined axial position and adapted to contact a plunger of a second syringe during attachment of the second syringe to the syringe interface, the plunger of the second syringe being at an axial position within the second syringe further rearward than the axial position of the plunger within the first syringe. 
   The syringe interface can further include a plunger interface that operates to transfer force between the injector and the plunger. In one embodiment, the plunger interface is slidably disposed within the plunger abutment. The plunger interface can include at least two radially outward extending connection flanges on a forward end thereof that cooperate with at least two relatively flexible capture members protruding from the rear of the plunger. The flexible capture members flex when contacted by the connection flanges to form a connection with the plunger interface. The piston interface can further include at least two sloped surfaces to the rear of the connecting flanges at an axial position in general alignment with the axial position of a radially inward projecting flange on the rearward end of each of the flexible capture members when the plunger is connected to the plunger interface. The radius of each of sloped surfaces can increase around the circumference thereof until the radius of each of the sloped surfaces is at least equal to the radius of one of the connecting flanges. 
   In still a further aspect, the present invention provides a syringe interface for attaching a first syringe to an injector. The first syringe includes a main body, a plunger slidably disposed within the main body and a mounting mechanism associated with the main body. The syringe interface includes: a retaining mechanism adapted to cooperate with the mounting mechanism of the first syringe and a plunger interface adapted to transfer force from the injector to the plunger. The plunger interface includes at least two radially outward extending connection flanges on a forward end thereof that cooperate with at least two relatively flexible capture members protruding from the rear of the plunger. The flexible capture members flex when contacted by the connection flanges to form a connection with the plunger interface. The piston interface includes at least two sloped surfaces to the rear of the connecting flanges at an axial position in general alignment with the axial position of a radially inward projecting flange on the rearward end of each of the flexible capture member when the plunger is in connection with the plunger interface. The radius of each of sloped surfaces increases around the circumference thereof until the radius of each of the sloped surfaces is at least equal to the radius of one of the connecting flanges such that, upon rotation of the plunger relative to the piston interface, the flexible capture members are flexed outwardly by contact of the radially inward extending flanges of the flexible capture member with the sloped surfaces until the radially inward extending flanges can pass forward of the connecting flanges of the piston interface, thereby enabling detachment of the plunger from the plunger interface. 
   The present invention, along with further aspects and attendant advantages, will best be understood by reference to the following detailed description taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  illustrates a cutaway view of an embodiment of an injector system of the present invention in which a syringe interface or adapter is attached to a powered injector. 
       FIG. 1B  illustrates a cross-sectional view of the injector system of  FIG. 1A  wherein a syringe is partially inserted into the syringe interface of the syringe adapter and in which the system has been rotated about its axis by approximately 90° as compared to the view of  FIG. 1A . 
       FIG. 1C  illustrates another cross-sectional view of the injectors system of  FIG. 1A  in the same orientation of  FIG. 1A  in which the syringe has been inserted to its rearward most position in the syringe interface of the syringe adapter. 
       FIG. 1D  illustrates a cutaway, perspective view of the syringe adapter of  FIG. 1A . 
       FIG. 2  illustrates a rear perspective, exploded or disassembled view of the syringe adapter of the injector system of  FIG. 1A . 
       FIG. 3A  illustrates a front perspective view of an embodiment of a syringe verification mechanism of the syringe interface of  FIG. 1A . 
       FIG. 3B  illustrates a rear perspective view of the syringe verification mechanism of  FIG. 3A . 
       FIG. 4A  illustrates a front perspective view of the assembled syringe adapter of the injector system of  FIG. 1A . 
       FIG. 4B  illustrates a rear perspective view of the assembled syringe adapter of the injector system of  FIG. 1A . 
       FIG. 5A  illustrates a perspective, partially cutaway view of a syringe attached to the syringe adapter of  FIG. 1A . 
       FIG. 5B  illustrates a perspective, cutaway view of the syringe adapter of  FIG. 1A   
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The syringe interfaces, adapters and injectors of the present invention are particularly suited for use with prefilled syringes as disclosed, for example, in U.S. Pat. No. 5,873,861, which are designed to contain an injection fluid for extended periods of time prior to an injection procedure. There are significant advantages in the use of syringes prefilled with injection fluid. For example, use of a prefilled syringe saves the user time, minimizes the potential for mislabeling of the liquid medium, minimizes the potential of contamination of the liquid medium and also minimizes the possibility of injecting air into the patient. 
   As discussed, for example, in U.S. Pat. No. 5,873,861, the material from which a prefilled syringe is fabricated is preferably chemically and biochemically compatible with the injection fluid for extended periods of time. The construction material(s) for the syringe should preferably exhibit good barrier properties, for example, low water vapor transmission rate, because changes in moisture content can detrimentally affect the ionic character of certain injection fluids. Moreover, unlike syringes designed to be filled after mounting on a powered injector, prefilled syringes containing injection fluid must be sterilized. Therefore, the construction material(s) for the syringe should also exhibit physical characteristics suitable to withstand the pressures, temperatures and other forces experienced during sterilization, such as autoclave sterilization. Further, like all syringes used in connection with powered injectors, the material of the syringe must have physical characteristics suitable to withstand pressure and other forces experienced during injection. Finally, it is desirable that the syringe material be clear so that the injection fluid contained in the syringe can be viewed. 
   While certain materials exhibit suitable long-term chemical and biochemical compatibility characteristics, such materials have often been found to be structurally weaker (that is, to have lower tensile strength and/or lower elasticity) than materials commonly used in front-loading, syringes used without pressure jackets. The syringes of U.S. Pat. No. 5,873,861 include multiple pairs of mounting flanges to enable fabrication of those syringes from a variety of fabrication materials (for example, polypropylene) to withstand the forces experienced in typical motorized injector applications. 
   An embodiment of a front-loading injector system  5  of the present invention is illustrated in, for example,  FIGS. 1A and 1B . Injector system  5  includes a powered injector  10  and at least one syringe  200  for injection of, for example, a contrast medium for use in a medical imaging procedure. Injector housing  30  of injector  10  preferably includes therein at least a first powered drive member or piston  40  which, for example, cooperates with syringe plunger  210  (via opening or passage  105  formed in a syringe interface or adapter  100  as illustrated, for example,  FIG. 1D ) to control the movement of plunger  210 , which is slidably disposed in syringe  200  to inject a fluid from the interior of syringe  200  into a patient. Multiple syringes can be attached to a single injector by providing, for example, multiple syringe interfaces and multiple drive members associated therewith. 
   As used herein to describe injection system  5  and other embodiments of the present invention, the terms “axial” or “axially” refer generally to, for example, axis A around which syringe  200  and piston  40  are preferably formed (although not necessarily symmetrically therearound) and to directions collinear with or parallel to axis A. The terms “proximal” or “rearward” refer generally to an axial or a longitudinal direction toward the end of injector housing  30  opposite the end to which syringe  200  is mounted. The terms “distal” or “forward” refer generally to an axial or a longitudinal direction toward a syringe tip  250  (from which pressurized fluid exits syringe  200 ). The term “radial” refers generally to a direction normal to an axis such as axis A. 
   In a number of respects, syringe interface or adapter  100  of injector system  5  operates in a manner similar to the operation of the syringe interface illustrated, for example, in  FIGS. 1B and 3B  of U.S. Pat. No. 5,873,861. In that regard, as illustrated, for example, in  FIGS. 1D and 4A , opening  105  of syringe interface  100  includes around the circumference thereof two pairs of opposed, axially extending slots  112  and  112 ′ and  118  and  118 ′. The centers of first pair of slots  112  and  112 ′ are positioned or rotated approximately 90° from the centers of second pair of slots  118  and  118 ′. Slots  112  and  112 ′ separate and define at least a first pair of radially inwardly projecting syringe retaining flanges  120  and  120 ′ formed around the circumference of the opening  105 . To the rear of first retaining flanges  120  and  120 ′ is a first circumferential groove or channel  124 , which is in communication with the axial slots  112  and  112 ′. 
   To the rear of channel  124 , are a second pair of radially inwardly projecting retaining flanges  128  and  128 ′. Retaining flanges  128  and  128 ′ are generally aligned with retaining flanges  120  and  120 ′. A second circumferential channel  130  (also in communication with slots  112  and  112 ′) is formed between the rear of mounting flanges  128  and  128 ′ and the forward surfaces of a third pair of retaining flanges  140  and  140 ′. A third circumferential channel  150  is formed to the rear of mounting flanges  140  and  140 ′. 
   Slots  118  and  118 ′ are formed in retaining flanges  120  and  120 ′ and  128  and  128 ′. Preferably, the depth of slots  118  and  118 ′ is somewhat less that the radial width of retaining flanges  120  and  120 ′. Slots  118  and  118 ′ preferably separate and frame third pair of radially inwardly projecting syringe retaining flanges  140  and  140 ′ formed around the circumference of opening  105  as discussed above. 
   Syringe  200  includes a body  220  having a rear portion which includes a first pair of radially extending mounting flanges  264  and  264 ′ and a second pair of radially extending mounting flanges  266  and  266 ′ (see, for example,  FIGS. 1C and 5A ). A radially extending drip flange  262  can be formed forward of first mounting flanges  264  and  264 ′ on body  250 . First mounting flanges  264  and  264 ′ and second mounting flanges  266  and  266 ′ are in general alignment. The structure of second mounting flanges  266  and  266 ′ is generally similar to the structure of first mounting flanges  264  and  264 ′. 
   Syringe body  220  also preferably includes a third pair of radially extending mounting flanges  270  and  270 ′. The centers of third mounting flanges  270  and  270 ′ are offset or rotated around the circumference of syringe body  250  approximately 90° (around axis A) from the centers of first mounting flanges  264  and  264 ′. 
   Opening  105  receives and firmly secures syringe  200  to syringe interface  100  and thereby to injector  10 . During mounting, third pair of mounting flanges  270  and  270 ′ pass through second pair of slots  118  and  118 ′, respectively. First pair of mounting flanges  264  and  264 ′ and second pair of mounting flanges  266  and  266 ′ pass through first pair of slots  112 ′ and  112 , respectively. Upon, for example, abutment of drip flange  262  with the front wall of syringe interface  100 , syringe  200  is fully rearwardly seated with syringe interface  100 , and syringe  200  is rotated clockwise relative to syringe interface  100  approximately 90° to firmly and releasably mount syringe  200  on injector housing  30  of injector  10 . A mechanical stop can be provided (for example, a radially inward projecting abutment in one or more of channels  124 ,  130  or  150 ) to prevent over-rotation of syringe  200 . Moreover, an audible click (or other indication) of proper rotation/full engagement of syringe  200  within syringe interface  100  can be provided. In the embodiment of  FIGS. 1A through 5B , for example, tabs  262   a  project rearward from flange  262  and seat within depressions  102  on a forward face of syringe interface  100  to cause an audible click when syringe  200  is fully/properly engaged with syringe interface  100 . To release syringe  200  from injector  20 , the process of mounting is simply reversed. 
   In the embodiment of  FIGS. 1A through 5B , syringe interface  100  includes a verification mechanism including a contact member  180  that is slidably biased (for example, via springs  181 ) within syringe interface  100 . When a syringe  200  is moved rearward into syringe interface  100 , flanges  266  and  266 ′ contact radially inward extending contacts or flanges  189  of contact member  180  (see, for example,  FIGS. 1C ,  3 A and  3 B) causing contact member  180  to move rearward within syringe interface  100  to the position illustrated in  FIG. 1C , once syringe  200  is moved to its rearward most position within syringe interface  100 . Contact member  180  further includes a base ring  184  from which extending members or extensions  188  extend axially forward. Mounting flanges  189  extends radially inward from the forward end of axial extensions  188 . Mounting flange abutment members  186 , positioned on each side of extensions  188  in the embodiment of  FIGS. 1A through 5 , also extend axially forward from base ring  184 . When contact member  180  is biased in its forward position as illustrated, for example, in  FIG. 1A , flange abutment members  186  extend axially forward into circumferential channel  150 . 
   When a rearward portion of syringe  200  is inserted into opening  105  of syringe interface  100 , mounting flanges  270  and  270 ′ pass through slots  118  and  118 ′, while generally aligned mounting flange sets  264  and  264 ′ and  266  and  266 ′ pass through slots  112  and  112 ′. Mounting flanges  266  and  266 ′ contact a forward surface of contact or abutment members  189  of contact member  180 . Contact of flanges  266  and  266 ′ with contact or abutment members  189  causes contact member  180  to move rearward within syringe interface  10 , thereby causing flange abutment members  186  to move out of channel  150  and allowing mounting flanges  270  and  270 ′ to be rotated within channel  150  to align with retaining flanges  140  and  140 ′ (to fully engage syringe  200  with syringe interface  100 ). In the embodiment of  FIGS. 1 through 5B , axially extending members  188  are slidably disposed within slots or channels  160  formed in syringe interface  100 . Channels  160  prevent contact member  180  from rotating relative to syringe interface  100 . 
   Verification mechanism  180  described above operates mechanically. It is apparent to one skilled in the art that the verification mechanism can operate in another manner, for example, electromechanically. In that regard, sensors (for example, switches, optical sensors etc.) as known in the art can be positioned within one or more of the slots of syringe interface  100  to ensure that one or more mounting flanges corresponding to mounting flanges  264 ,  264 ′,  266 ,  266 ′,  270  or  270 ′ are present upon a syringe. 
   Syringe interface  100  further includes a generally cylindrical core member or abutment member  170  disposed within syringe interface  100 . In the embodiment of  FIGS. 1A through 5B , abutment member  170  extends into the interior of syringe  200  (see, for example,  FIGS. 1B and 1C ) to a predetermined axial position within syringe  200 . 
   In the embodiment of  FIGS. 1A through 5B , slidably disposed within core member or abutment member  170 , is a plunger interface  190  that operates to transfer force between drive member  40  and plunger  210 . Plunger interface  190  includes a forward portion including a plunger attachment having one or more radially outward extending flanges  192  that cooperates with rearward projecting flex legs  212  of plunger  210  to releasably attach plunger interface  190  to plunger  210 . The operation of flex legs  212  is described, for example, in U.S. Pat. Nos. 5,873,861 and 5,947,935, assigned to the assignee of the present invention, the disclosures of which are incorporated herein by reference. In general, as plunger  210  is moved rearward relative to plunger interface  190  (or plunger interface  190  is move forward relative to plunger  210 ), flex legs  212  contact flanges  192  and flex radially outward to a stressed state to allow further rearward movement of plunger  210  relative to plunger interface  190 . Once ledges or flanges  214  formed on flex legs  212  pass rearward of the rearward surfaces of flanges  192 , flex legs  212  snap or otherwise return inward engage flanges  192  of plunger interface  190 . 
   To facilitate disconnection of plunger interface  190  from plunger  210 , plunger interface  190  includes, to the rear of flanges  192 , sloped surfaces  194 . The radii of sloped surfaces  194  increase around the circumference thereof until the radii are at least equal to the radii of flanges  192 . During connection of plunger  210  to plunger interface  190 , plunger interface  190  is aligned about its axis relative to the alignment of plunger  210  about its axis so that flex legs  212  are aligned with an area of sloped surfaces  194  of reduced radius to allow radially inward projecting flanges  216  of flex legs  212  to be in a inward position in which ledges  214  abut a rearward surface of flanges  192 . In this position, plunger  210  cannot be moved axially forward relative to plunger interface  190 . To allow disengagement of plunger interface  190  from connection with plunger  210 , syringe  200  (and thereby plunger  210 ) is rotated relative to plunger interface  190  so that flanges  216  travel along sloped surfaces  194 , gradually forcing flex legs  212  to a radially outward position until ledges  214  no longer abut a rearward surface of flanges  192  and plunger  210  can be move axially forward relative to plunger interface  190  for disconnection therefrom. 
   Flanges  192  can be appropriately axially positioned and rotated about axis A to an appropriate position such that a secure engagement is formed between plunger  210  and plunger interface  190  at the same time that syringe  200  engages with syringe interface  100 . In that regard, when syringe  200  is moved axially rearward to fully seat within syringe interface  100 , the rearward surfaces of flanges  192  are preferably generally aligned to engage ledges  214 . Further, when syringe  200  is rotated about its axis to align mounting flanges on the syringe with retaining flanges on syringe interface  100  as described above, flanges  214  of flex legs  212  are generally aligned with areas of sloped surfaces  194  of reduced radius to allow flanges  216  to be in a radially inward positions in which ledges  214  abut the rearward surfaces of flanges  192  as illustrated, for example, in  FIG. 1C . To prevent plunger interface  190  from rotating relative to syringe interface  100  when syringe  100  is rotated, plunger interface  190  is, in the embodiment of  FIGS. 1A through 5B , formed to have a non-circular shape (for example, the shape of a hexagon), which cooperates with a corresponding non-circular (for example, hexagonal) shaped passage  172  (see, for example,  FIG. 2 ) formed in core  170 . 
   In an alternative embodiment, a sensing system is provided to signal the control system of injector  10  a known amount of time before flange  192  is engaged by flex legs  212  so that the control system stops advancement of piston  40  after a secure connection is made between plunger interface  190  and plunger  210 , but before piston  40  is advanced to a degree to cause injection of fluid from the interior of syringe  200 . A sensing system for “auto docking” of a piston to a syringe plunger is described generally, for example, in U.S. patent application Ser. No. 10/159,592, filed May 30, 2002, assigned to the assignee of the present invention, the disclosure of which incorporated herein by reference. 
   In the embodiment of  FIGS. 1A through 5B , plunger interface  190  includes a biased sensing pin  196  (biased, for example via a spring  197 ) slidably disposed therein. Sensing pin  196  extends forward of the forward surface of flanges  192 . Sensing pin  196  is in operative connection with a biased sensing pin  42  (for example, spring-loaded via spring  44 ) projecting from piston  40 . As piston  40  (and thereby plunger interface  190 ) is advanced forward toward plunger  210  sensing pin  196  contacts a rearward or inward surface of plunger  210 . Sensing pin  196  transfers the resultant force to pin  42 , and pin  42  is forced rearward so that it, for example, impinges upon the field of a sensor such as an optical sensor (not shown). As described above, the sensor can signal the control system of injector  10  so that the control system stops advancement of piston  40  after a predetermined amount of time or distance of advancement of piston  40 , so that piston  40  is brought into operative engagement with plunger  210  (via intermediate plunge interface  190 ), but advancement of piston  40  is stopped before movement of syringe plunger  210 . The amount of time between such a signal and the cessation of piston movement can, for example, depend on compliance or tolerance within the piston drive mechanism and plunger interface  190  as well as the type of syringe attached to interface  100 . 
   Piston  40  can, for example, include retractable pins  46  that form an abutting connection with one or more ledges, flanges or grooves  198  formed around the interior circumference of plunger interface  190  when piston  40  is to be retracted, thereby causing plunger interface  190  (and, thereby, syringe plunger  210 ) to retract or move rearward along with piston  40 . 
   During advancement of piston  40  to engage plunger  210 , as well as during advancement of piston  40  to advance plunger  210  within syringe  200  (for example, to expel air or injection fluid contained within syringe  100 ), pins  46  are preferably in a retracted state. In this state, a forward facing surface  43  of piston  40  abuts a rearward surface  195  of plunger interface  190  during forward movement of piston  40  to force plunger interface  190  (and thereby plunger  210 ) forward. As described above and in U.S. patent application Ser. No. 10/159,592, if retraction of plunger  210  is desired, pins  46  are extended to abut ledge  198 . 
   Syringe interface  100  can, for example, be connected directly to or be an integral part of an injector. In the embodiment of  FIGS. 1A through 5B , however, syringe interface  100  includes or is in operative connection with an adaptive section including a connector  300  for releasably engaging syringe interface  100  with an injector. Adaptive section, connector or injector interface  300  for use with syringe interface  100  of the present invention allows the use of syringe  200  with many different types of injectors originally designed for use with syringes having an injector interface, mounting mechanism or connector different from that of syringe  200 . In the embodiment of  FIGS. 1A through 5B , flange  320  of connector  300  described above, for example, is designed to cooperate with a front-loading injector and release mechanism as described, in at least one embodiment, in PCT Publication No. WO 01/37903 and U.S. Pat. No. 6,652,489, each assigned to the assignee of the present invention, the disclosures of which are incorporated herein by reference. In the embodiment of  FIGS. 1A through 5B , flange  320  encompasses the entire circumference of injector connector  300 . 
   The rearward end of connector  300  includes indicators  310  that can cooperate with a light source and sensors to provide information about the configuration of syringe interface  100 , as described in U.S. patent application Ser. No. 09/765,498, filed on Jan. 18, 2001, assigned to the assignee of the present invention, the disclosure of which is incorporated herein by reference. 
   Although the present invention has been described in detail in connection with the above embodiments and/or examples, it should be understood that such detail is illustrative and not restrictive, and that those skilled in the art can make variations without departing from the invention. The scope of the invention is indicated by the following claims rather than by the foregoing description. All changes and variations that come within the meaning and range of equivalency of the claims are to be embraced within their scope.