1. A method of scanning an image to detect regions of interest comprising the steps of: calculating 3-D gradient vectors for voxels in a window of interest of the image; applying a transform to the gradient vectors to create a transform output; classifying the transform output into output regions, which such regions represent a different range of gradient intensity values and a different range of probabilities concerning the direction of a gradient vector; measuring the number of directed gradients associated with the output regions' classifying the output