1. From the Department of Radiology, UT Southwestern Medical Center, Dallas, Tex (A.C.); Department of Cardiology, University of Iowa Stead Family Children’s Hospital, Iowa City, Iowa (R.A.); Department of Radiology, University of Michigan, Ann Arbor, Mich (P.P.A.); and Department of Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (C.F., P.R.).