1. From the Departments of Medicine/Cardiology (S.N., A.K., M.M.Z., G.R.M., R.K., A.R., T.L.D., H.A., H.C., R.D.B., D.A.B., A.C.L., H.R.H.), Radiology (D.A.B., H.R.H.), Radiation Oncology (R.C.S.), and Biomedical Engineering (R.D.B., A.C.L., H.R.H.), Johns Hopkins Hospital, Baltimore, Md.