1. From the Cardiac MR PET CT Program (S.K.S., Q.A.T., F.B., I.S.R., M.D.S., C.L.S., C.U.C., R.C., S.A., T.J.B., U.H.), Department of Radiology and Division of Cardiology, and the Department of Emergency Medicine (J.T.N.), Massachusetts General Hospital and Harvard Medical School, Boston Mass.