1. From the National Institutes of Health Clinical Center, National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD (E.B.T., D.A.B.); Biostatistics Center, George Washington University, Rockville, MD (J.-Y.C.B., P.A.C., J.M.L.); Case Western Reserve University, Department of Medicine, Cleveland, OH (S.G.); Department of Radiology (E.B.T., A.J., C.-Y.L., D.A.B.) and Division of Cardiology, Departments of Medicine and Radiology (J.A.C.L.), Johns Hopkins University, Baltimore, MD;...