The fluid injection apparatus for use with the syringe includes an injector and a pressure jacket assembly associated with the injector. The injector includes a housing defining a central opening and a drive piston extendable through the central opening for imparting motive forces to a syringe plunger disposed within the syringe. The pressure jacket assembly includes a pressure jacket and at least one locking member pivotally associated with the pressure jacket. The at least one locking member is movable between an engaged position preventing removal of the syringe from the pressure jacket and a disengaged position allowing insertion and removal of the syringe into the pressure jacket.