1. From the Department of Neurology (D.S., H.B., F.A., D.S.K., R.C.P., B.F.B., K.A.J., J.G.-R.), and Department of Radiology (N.T.T.P., J.W.), Mayo Clinic, Rochester, MN; Department of Neuroscience (S.K., N.K., M.E.M., D.W.D.), Mayo Clinic, Jacksonville, FL; Department of Quantitative Health Sciences (R.C.P., W.K.K.), and Department of Laboratory Medicine and Pathology (A.T.N., R.R.R.), Mayo Clinic, Rochester, MN; and Department of Neurology (N.G.-R.), Mayo Clinic, Jacksonville, FL.