1. From the Cardiovascular Imaging Laboratory, Division of Radiological Sciences, Department of Radiology (A.R.C., J.L.L., L.R.P.), Cardiovascular Division, Department of Medicine (J.L.L., A.K., D.P.T., S.R., K.M., S.P., M.F., L.R.P.), and Center for Applied Research Sciences (C.A.S.), Washington University School of Medicine, St. Louis, MO.