An imaging system and method acquires non-contrast images of a region of interest in a body and determines an entrance criterion based on the non-contrast images. The entrance criterion dictates conditions in which to begin acquiring contrast imaging exposures of the region of interest. An amount of a contrast agent is measured in one or more locations in the imaged body subsequent to acquiring the non-contrast images. The system and method determine that the one or more conditions of the entrance criterion are met based on the amount of the contrast agent that is measured in the imaged body, and acquire one or more contrast images of the region of interest in the imaged body responsive to determining that the one or more conditions of the entrance criterion are met.