1. From the Department of Radiology and Radiological Sciences (K.K.P.L, V.B.P., C.H.P., M.M.) and Department of Obstetrics and Gynecology (L.C.Z.), Vanderbilt University Medical Center, 1161 21st Ave South, Nashville, TN 37232; and Department of Diagnostic Imaging and Radiology, University of Louisville, Louisville, Ky (J.M.O.).