A system (825) and method for collection and re-use of a fluid medium derived from the diversion of at least some of an injection of the medium to a selected site within a patient's body are described. The system includes a sterile medium container (328), a flow diverter assembly (575) disposed in a fluid medium flow path between an injection syringe (332) and a medium delivery catheter (334), and a diversion reservoir (827, 827a, 827b) having a reservoir chamber (860, 834) for receiving the diverted portion of the fluid medium from the flow diverter assembly (575) and a fluid coupling (588b) to the sterile medium container (328). The flow diverter assembly (575) is configured to divert at least a portion of a fluid medium injection from the medium flow path between the syringe (332) and the delivery catheter (334) during injection. The diversion reservoir (827, 827a, 827b) is configured so as to preferentially allow re-use of the diverted medium in the reservoir chamber (860, 834) prior to allowing use of the medium in the sterile medium container (328).
