Magnetic resonance imaging and endometriosis: deeply infiltrating endometriosis does not originate from the rectovaginal septum.

The goal of this study was to describe the magnetic resonance (MR) imaging signs of deeply infiltrating endometriosis (DIE) lesions and above all to find out if MR imaging can pinpoint the location of these lesions. We made a retrospective study of 8 patients presenting with histologically proven DIE lesions. The MR imaging results were compared with intraoperative findings. Nodules revealed on T1-weighted images as isointense to myometrium with hyperintense spots remained visible on the fat-suppressed spin echo images. When there was no rectal involvement, the T1- and T2-weighted images showed a hypointense transition area between the nodule and the rectum. The DIE nodules were in identical locations in every case, lying below the torus uterinum, level with the posterior vaginal fornix and the upper third of the posterior vaginal wall. Without exception, the DIE nodules were located above the upper edge of the rectovaginal septum, with the latter appearing fine and regular with no image of any nodule. Our MR imaging results suggest that DIE lesions do not originate from the rectovaginal septum.