1. From the Department of Radiology, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, 676 N St Clair St, Suite 800, Chicago, IL 60611 (C.L.V., M.J.M., F.H.M.); Department of Radiology, Medical College of Georgia, Augusta, Ga (P.K.M.); and Department of Radiology and Imaging Sciences, Emory University, Atlanta, Ga (C.C.M.).