1. From the Mallinckrodt Institute of Radiology (K.F.F., K.S.K., P.K.W., S.B.), and Department of Pulmonology (T.D.R.), Washington University School of Medicine, 510 S Kingshighway Blvd, St Louis, MO 63110; Department of Radiology, Mayo Clinic, Phoenix, Ariz (C.E.J.), and Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tenn (K.J.L.).