1. From the Department of Radiology, Massachusetts General Hospital, 55 Fruit St, Ellison 237, Boston, Mass 02114 (M.S.G., S.I.L.); Department of Medical Imaging, University of Toronto, Toronto, Canada (M.A.); Department of Biostatistics, University of Pittsburgh, Pittsburgh, Pa (A.I.B.); Department of Obstetrics and Gynecology, University of Oklahoma Health Science Center, Oklahoma City, Okla (R.S.M.); and Department of Obstetrics and Gynecology, Tulsa Cancer Institute, Tulsa, Okla (M.A.G.).