1. From the Department of Neurology (A.L.F., P.B., J.M.L.), Division of Biostatistics (G.D.), and Department of Radiology (R.P., K.D.V.), Washington University, School of Medicine, St. Louis, MO; Department of Radiology (H.A., W.L.) and Department of Neurology (W.J.P.), University of North Carolina at Chapel Hill, Chapel Hill, NC.