1. From the Department of Radiology (P.P.A., S.P.), Department of Internal Medicine, Division of Cardiology (T.L.), and Department of Cardiac Surgery (B.Y.), University of Michigan Health System, 1500 E Medical Center Dr, Ann Arbor, MI 48109; Department of Radiology, University of Ottawa, Ottawa, Ont, Canada (C.D., E.P.); and Department of Radiology, University of Toronto, Toronto, Ont, Canada (E.N.).