1. From the Department of Radiology and Biomedical Imaging (G.R.C., T.L., T.L.C., G.B.J., M.V., Y.J.L., T.H.V., Y.S., A.M.R., J.H.S.) and Department of Epidemiology and Statistics (C.E.M.), University of California San Francisco, 505 Parnassus Ave, San Francisco, CA 94143.