A syringe plunger includes a wall having an inner surface and one or more inwardly projecting flanges disposed on the inner surface of the wall. Preferably, the inner surface of the wall defines a retaining shoulder formed along an axial plane thereof. An injector drive member preferably includes at least one retaining member adapted to engage the retaining shoulder of the syringe plunger to allow the drive member to retract the plunger with the body of the syringe. Further, the drive member preferably includes one or more outwardly extending flange members adapted to be engaged by the inwardly projecting flanges of the syringe plunger. When the syringe body is rotated, the at least one retaining member on the drive member is retracted and disengaged from the retaining shoulder of the syringe plunger.