1. From the Department of Radiology (A.W.K., B.P.S., B.C.L., M.W.), Neuroradiology Section, the Department of Emergency Medicine (W.S.F.), and the Department of Epidemiology and Biostatistics (S.C.), University of California, San Francisco, San Francisco, CA; the Department of Radiology (S.A.), University of Louisville Hospital, Louisville, KY; the Harvard Neurology Residency Program (R.M.), Harvard Medical School, Boston, MA; the Department of Radiology (M.W.), Neuroradiology Division, University of...