A rolling diaphragm syringe includes a proximal end having an end wall, a distal end having an open-ended discharge neck, a sidewall extending along a longitudinal axis, and a piston engagement portion protruding proximally from a central portion of the end wall and configured for engagement with a piston of a fluid injector. The piston engagement portion has a stem with a first end attached to the end wall, a second end extending proximally from the first end, and at least one protrusion that protrudes radially outward. The sidewall is flexible and rolls upon itself when acted upon by the piston such that an outer surface of the sidewall is folded in a radially inward direction as the piston is advanced from the proximal end to the distal end, and unfolded in a radially outward direction as the piston is retracted from the distal end to the proximal end.