1. An imaging work station comprising: one or more processors programmed to: receive an image depicting a distribution of a radiotracer in a region of interest that includes the brain; register the image to a common space defined by a template or an MRI image of the region of interest, the common space including a segmented anatomical feature representing a probability that each voxel is gray matter; and extract a volume representation of the image which depicts the distribution of the radiotracer in the segmented anatomical feature and suppresses the radiotracer outside of the segmented anatomical feature by combining each voxel of the image with the probability of the voxel being gray matter as represented by the registered common space.