1. From the Department of Radiology (M.Y., A.D.T.A., Z.S.K., M.L.W., J.P.H., S.P.S., J.L.F., S.K.V.) and Department of Laboratory Medicine and Pathology (M.S.T.), Mayo Clinic, 200 2nd St SW, Rochester, MN 55905; and Department of Diagnostic Imaging, National University Health System, Singapore (L.L.S.T.).