1. From the Department of Radiology (C.T.L., A.H., E.K.F., S.L.Z.), Department of Medicine, Cardiology Division (M.J.C., R.K.H., J.R.R.), and Department of Medicine, Pulmonary and Critical Care Division (B.T.G.), Johns Hopkins University School of Medicine, 601 N Caroline St, JHOC 3171B, Baltimore, MD 21287.