1. From the Department of Radiology & Biomedical Imaging, Division of Interventional Neuroradiology (K.H.N., B.F.K., D.M., A.C., J.M., M.R.A., C.F.D., V.V.H., R.T.H., T.M., M.W.W., D.L.C., S.W.H.), and Department of Neurology (J.V., C.H.S.), University of California San Francisco, 505 Parnassus Ave, L-351, San Francisco, CA 94143-0628; and Siemens Medical Solutions, Malvern, Pa (K.M., H.B.).