1. A method of analyzing a selected region of interest in medical image data of a subject, comprising: obtaining an initial image data set; filtering the initial image data set to generate a filtered data set, wherein the step of filtering comprises computing, for each voxel of the initial image data set, a value of intensity for a standardized volume of interest centered on that voxel; registering a user selection of a region of interest in the initial image data set; and computing from the filtered image data set a value of intensity for the selected region of interest.