1 From the Department of Radiology, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave, MC 3252, Madison, WI 53792-3252 (J.P.K.); Department of Radiology, Massachusetts General Hospital, Boston, Mass (B.P.L.); Department of Radiology, University of Chicago, Chicago, Ill (J.H.C.); Department of Radiology, University of California San Francisco, San Francisco, Calif (B.M.E.); and Department of Radiology, University of New Mexico, Albuquerque, NM (L.H.K.).