1. From the Department of Radiology, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI 53792-3252 (A.M.F.); Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pa (D.A.M.); and Department of Radiology and Biomedical Imaging, University of California–San Francisco School of Medicine, San Francisco, Calif (B.N.J.).