1. Department of Medicine, Cardiology Division (J.R.G., A.G.H., T.J.S., G.G., R.G.W.), Johns Hopkins University School of Medicine, Baltimore, MD.
2. Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston (R.E.G.).
3. Department of Radiology, Division of MR Research (M.S., P.A.B., R.G.W.), Johns Hopkins University School of Medicine, Baltimore, MD.
4. Division of General Internal Medicine (L.R.Y.), Johns Hopkins University School of Medicine, Baltimore, MD.