1. From the Department of Radiology, UT Southwestern Medical Center, Dallas, Tex (A.C.); Department of Radiology, UT Health Sciences Center, Houston, Tex (D.O.T.); Department of Radiology, University of Colorado, Aurora, Colo (D.V.); and Department of Radiology (T.A.F., P.S.R.) and Division of Cardiology (A.K.C.), Mayo Clinic, 200 First St SW, Rochester, MN 55905.