1. An apparatus for ultrasonically scanning a breast, comprising: an essentially planar radial scanning template configured to contact and compress and flatten the breast chestwardly while the breast is facing up, wherein the template has a rounded periphery and a nipple hole configured for a breast nipple to protrude upwardly therethrough, and the template has one or more elongated, slot-shaped openings extending from the nipple hole toward a periphery of the template; one or more elongated ultrasound transducers each aligned with a respective one of the one or more slot-shaped openings; said template being configured to rotate over the breast while compressing the breast, and said one or more transducers being configured to rotate with the template to scan the breast ultrasonically through the respective one or more slot-shaped openings and to generate 2D ultrasound images of the breast; an actuator configured to automatically rotate the template for said scanning; and a computer-implemented image processing and display facility associated with the one or more transducers and configured to receive and process the 2D images into images of slices of the breast that have selected thicknesses and orientations, and further configured to display, under operator control, at least one or more images selected from the slice images.