From the Departments of Medicine (K.A.A., J.V.C., E.E.F., M.K.M.), Radiology (J.-A.O.S.), and Pathology (J.A.S.), Massachusetts General Hospital, and the Departments of Medicine (K.A.A., J.V.C., E.E.F., M.K.M.), Radiology (J.-A.O.S.), and Pathology (J.A.S.), Harvard Medical School - both in Boston.