From the Department of Radiology (S.B.P., M.T.L., T.M., T.L., A.P., B.B.G., Q.A.T., U.H., M.F.), Cardiac MR PET CT Program (S.B.P., M.T.L., T.M., T.L., A.P., B.B.G., Q.A.T., U.H., M.F.), and Cardiology Division (Q.A.T., M.F.), Massachusetts General Hospital and Harvard Medical School, 165 Cambridge St, Suite 400, Boston, MA 02114; Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria (S.B.P.); Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass (S.D.W.); and Division of Cardiovascular Sciences, National Heart, Lung and Blood Institute, Bethesda, Md (J.L.F.).