1. From the Department of Radiology, University of Alabama at Birmingham, 619 S 19th St, JT N450, Birmingham, AL 35249 (F.N.T.); Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Mo (W.D.M.); and Department of Radiology, Keck School of Medicine, University of Southern California, Los Angeles, Calif (E.G.G.).