1. A method of delivering a contrast enhancing fluid to a patient using an injector system, comprising: determining at least one patient transfer function for the patient based upon data specific to the patient, the at least one patient transfer function providing a time enhancement output for a given input; determining a desired time enhancement output; using the at least one patient transfer function to determine an injection procedure input; and controlling the injector system at least in part on the basis of the determined injection procedure input.