1. From the Department of Diagnostic Radiology (H.T., T.A.P., B.K.) and Department of Laboratory Medicine and Pathology (J.C.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905; Department of Radiology, Mayo Clinic, Scottsdale, Ariz (A.K.); and Department of Diagnostic Radiology, University of Tsukuba, Tsukuba, Japan (S.M.).