1. From the Department of Radiology and Imaging Sciences, Emory University, 550 Peachtree Rd, Atlanta GA 30308 (B.T.L., K.D.H., S.A.H., T.N.H.); Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, Calif (T.H.); Department of Radiology, Harvard Medical School, Boston, Mass (B.P.L.); Department of Radiology, Denver Health and Hospital Authority, Denver, Colo (D.M.N.); and Department of Radiology, University of Colorado, Denver, Colo (D.M.N.).