1. From the Department of Radiology, Massachusetts General Hospital, 55 Fruit St, White 270, Boston, MA 02114 (D.D.B.B., H.Y.); Department of Radiology, Boston University Medical Center, Boston, Mass (D.D.B.B., K.G., H.Y., A.M.M., B.N.S., S.W.A., M.O.C.); and Department of Radiology, Brigham and Women’s Hospital, Boston, Mass (J.U.).