An imaging system including a closed-loop controller (FC) for automatically adapting a power injector system (PJ). The power injector (PJ) injects contrast agent into an object (V) and the imager (100) acquires one or more images (AN, AN i) of the object (V) with the contrast agent resident therein. The controller (FC) calculates a desired optimal injection rate from the images (AN, ANi). Controller (FC) then controls the injector (PJ) according to the calculated optimal injection rate.