1. From the Department of Radiology, University of Wisconsin School of Medicine and Public Health, E3/311 Clinical Sciences Center, 600 Highland Ave, Madison, WI 35792 (M.G.L., P.J.P.); Department of Radiology, University of Mississippi Medical Center, Jackson, Miss (A.D.S.); Department of Radiology, Indiana University School of Medicine, Indianapolis, Ind (K.S.); and Department of Radiology, Harvard Medical School, Boston, Mass (D.V.S.).