1. From the Cardiothoracic Imaging Division, Department of Radiology, University of Michigan, Taubman Center B1-132D, 1500 E Medical Center Dr, Ann Arbor, MI 48109-5302 (M.M.H.S., E.C.S., G.E.M., L.E.Q., P.P.A.); and Abdominal Imaging Division and Michigan Radiology Quality Collaborative, Department of Radiology, University of Michigan, Ann Arbor, Mich (P.R.S.).