1. From the Department of Clinical Neurosciences (S.B.C., P.A.B., A.M.D., M.D.H., J.H.W.P., M.E.H., A.M.B.) and Radiology (M.E.H.), University of Calgary; Seaman Family MR Centre (S.B.C., A.M.D., J.H.M.P.); and Departments of Medicine and Community Health Sciences, Foothills Medical Centre (M.D.H.), Calgary, Alberta, Canada.