A syringe for use with an injector includes a body comprising a distal discharge end, a plunger movably disposed within the body, and an agitation element disposed within the body between the plunger and the distal discharge end. A movement mechanism is operably associated with the injector to move the syringe in such a way that the at least one agitation element agitates a fluid contained in the syringe. Preferably, the syringe contains an ultrasound contrast agent that is agitated by the agitation element. An injector system and a method for agitating the contents of a syringe are also provided.