1. From the Departments of Medicine (M.E.S., M.V.B., E.P.R.) and Radiology (J.-A.O.S.), Massachusetts General Hospital, and the Departments of Medicine (M.E.S., M.V.B., E.P.R.) and Radiology (J.-A.O.S.), Harvard Medical School — both in Boston; and the Department of Medicine, Columbia University Irving Medical Center, and the Department of Medicine, Vagelos College of Physicians and Surgeons — both in New York (J.S.S.).