1. From the Department of Radiology and Biomedical Research Imaging Center (H.A., W.L.), University of North Carolina at Chapel Hill, Chapel Hill, NC; the Departments of Neurology (A.L.F., J.-M.L.) and Radiology (K.V.), Washington University, School of Medicine, St Louis, MO; and the Department of Neurology (W.J.P.), University of North Carolina at Chapel Hill, Chapel Hill, NC.