1. From the Departments of Radiology (L.K.S., R.B.J., E.W.O.) and Pathology (G.J.B.), Stanford University School of Medicine, 300 Pasteur Dr, Room H1307, Stanford, CA 94305-5105; and Department of Radiology, Veterans Affairs Palo Alto Health Care System, Palo Alto, Calif (L.K.S., E.W.O.).