1. From the Center for Evidence-Based Imaging (Z.Y., I.K.I., A.S.R., A.G., R.K.), Department of Radiology (A.S.R., A.G., R.K.), Department of Medicine (I.K.I.), and Department of Emergency Medicine (A.G., J.M.K.), Brigham and Women’s Hospital, Harvard Medical School, 20 Kent St, 2nd Floor, Boston, MA 02120; and Department of Emergency Medicine, Massachusetts General Hospital, Boston, Mass (A.S.R.).