1. From the Departments of Radiology (F.H.M., C.L.V., H.S.R., C.G.W., H.G., A.A.B., P.N., N.A.H.) and Gastroenterology (R.N.K.), Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, 676 N St. Clair Street, Suite 800, Chicago, IL 60611; and Department of Radiology, Medical College of Georgia, Augusta, Ga (P.M.).