1. A method, comprising: scanning a region of interest, during a contrast agent based perfusion scan, at a predetermined temporal sampling rate during contrast agent uptake in the region of interest, and generating time frame data indicative of the scanned region of interest; identifying a predetermined change in an amount of contrast agent in the region of interest from the time frame data; and scanning the region of interest at a lower temporal sampling rate, which is lower than the temporal sampling rate during the contrast agent uptake, in response to identifying the predetermined change in the amount of the contrast agent in the region of interest wherein the lower temporal sampling rate varies during scanning the region of interest.