1 From the Department of Radiology, Division of Cardiothoracic Radiology (G.Y., E.A.K., E.M.L., P.P.A.), and Department of Cardiac Surgery (M.D.), University of Michigan Hospital, 1500 E Medical Center Dr, Ann Arbor, MI 48109; and Department of Radiology, Division of Cardiothoracic Radiology, Rush University Medical Center, Chicago, Ill (P.N.S.).