1. From the Department of Radiology, UT Southwestern Medical Center, Dallas, Tex (P. Ranganath); Department of Radiology, Baylor University Medical Center, Dallas, Tex (A.M.); and Department of Cardiology (M.G.) and Department of Radiology (J.C., T.F., E.W., P. Rajiah), Mayo Clinic, 200 1st St SW, Rochester, MN 55905.