A medical imaging system (5) includes one or more processors and a display device (36). The one or more processors are programmed to receive (60) a first image (10) contrasting regions of tissue with a distinct radiotracer accumulation probability and generate (64) a constraint map (20) based on the regions of tissue with the distinct radiotracer accumulation probability. The one or more processors are programmed to reconstruct (70) a second image (44) with redistribution of a measured radiotracer based on the constraint map (20) and acquired image raw data (23) registered to the constraint map. The display device (36) displays the reconstructed second image.