1. From the Mallinckrodt Institute of Radiology (M.J.H., B.S.S., D.H.B., C.L.S., A.S.S., V.M.M.) and Department of Pathology (R.C.W.), Washington University School of Medicine, Campus Box 8131, 510 Kingshighway Blvd, St Louis, MO 63110; and Department of Radiology (M.Y., A.K., M.Z.) and Department of Laboratory Medicine and Pathology (M.L.S.), Mayo Clinic Arizona, Scottsdale, Ariz.