From the Centers for Systems Biology (M.N.) and Molecular Imaging Research (M.N., D.E.S., F.K.S.), and Cardiology Division (D.E.S.), Massachusetts General Hospital and Harvard Medical School, Boston, Mass; Department of Biomedical Engineering (B.A.F.), University of Virginia, Charlottesville, Va; Radiology and Cardiovascular Nuclear Medicine (F.B.), Johns Hopkins University School of Medicine, Baltimore, Md; Cardiovascular Molecular Imaging Laboratory (M.M.S), Section of Cardiovascular Medicine, Yale University School of Medicine, and VA Connecticut Healthcare System, New Haven, Conn; Cardiovascular Division (J.R.L.), Oregon Health and Science University, Portland, Ore; Departments of Medicine (Cardiology) and Radiology (Molecular Imaging Program at Stanford) (J.C.W.), Stanford University School of Medicine, Stanford, Calif; Russell H. Morgan Department of Radiology and Radiological Science (D.L.M.), The Johns Hopkins University School of Medicine, Baltimore, Md; Translational and Molecular Imaging Institute (Z.A.F.), Mount Sinai School of Medicine, New York, N.Y.; and Department of Medicine and Diagnostic Radiology (A.J.S.), Yale University School of Medicine, New Haven, Conn.