A syringe (12, 7900) adapted for use with a fluid injector having a housing and a piston at least partially disposed within the housing, the piston having one or more retractable pins and one or more outwardly extending flange members on an abutment section, the syringe (12, 7900) comprising: a body; and a plunger (38, 7910) movably disposed within the body, the plunger (38, 7910) comprising: a substantially cylindrical wall having a circumferentially continuous inner surface and an outer surface, characterized in that the inner surface defines a retaining shoulder formed circumferentially along an axial length thereof and extending therefrom in a radial direction along the circumference of the inner surface, and the plunger (38, 7910) further comprises an annular rear base member and a forward cover, the annular rear base member having a plurality of inwardly projecting flanges spaced around the inner surface, the inwardly projecting retaining flanges extending rearward from the retaining shoulder and are fixedly disposed on the inner surface of the substantially cylindrical wall and extending longitudinally along a portion of the interior surface of the substantially cylindrical wall, the one or more retractable pins of the piston are adapted to form an abutting connection with the retaining shoulder when the piston is retracted to retract the plunger therewith, and the inwardly projecting flanges are adapted to engage the one or more outwardly extending flange members such that the one or more retractable pins disengage the retaining shoulder when the body is rotated about its longitudinal axis. a body; and a plunger (38, 7910) movably disposed within the body, the plunger (38, 7910) comprising: a substantially cylindrical wall having a circumferentially continuous inner surface and an outer surface, characterized in that the inner surface defines a retaining shoulder formed circumferentially along an axial length thereof and extending therefrom in a radial direction along the circumference of the inner surface, and the plunger (38, 7910) further comprises an annular rear base member and a forward cover, the annular rear base member having a plurality of inwardly projecting flanges spaced around the inner surface, the inwardly projecting retaining flanges extending rearward from the retaining shoulder and are fixedly disposed on the inner surface of the substantially cylindrical wall and extending longitudinally along a portion of the interior surface of the substantially cylindrical wall, the one or more retractable pins of the piston are adapted to form an abutting connection with the retaining shoulder when the piston is retracted to retract the plunger therewith, and a substantially cylindrical wall having a circumferentially continuous inner surface and an outer surface, characterized in that the inner surface defines a retaining shoulder formed circumferentially along an axial length thereof and extending therefrom in a radial direction along the circumference of the inner surface, and the plunger (38, 7910) further comprises an annular rear base member and a forward cover, the annular rear base member having a plurality of inwardly projecting flanges spaced around the inner surface, the inwardly projecting retaining flanges extending rearward from the retaining shoulder and are fixedly disposed on the inner surface of the substantially cylindrical wall and extending longitudinally along a portion of the interior surface of the substantially cylindrical wall, the one or more retractable pins of the piston are adapted to form an abutting connection with the retaining shoulder when the piston is retracted to retract the plunger therewith, and the inwardly projecting flanges are adapted to engage the one or more outwardly extending flange members such that the one or more retractable pins disengage the retaining shoulder when the body is rotated about its longitudinal axis.