Purpose: To determine the accuracy of 3.0-T pelvic magnetic resonance (MR) imaging in the preoperative assessment of endometriosis and to evaluate colon wall involvement after intrarectal gel administration.
Materials and methods: Institutional review board approval for this study was obtained, and each patient gave written informed consent. Forty-one consecutive patients with clinical suspicion of endometriosis underwent pelvic MR imaging at 3.0 T before surgery. Single-shot and high-spatial-resolution axial T2-weighted, sagittal fat-suppressed T2-weighted, and axial fat-suppressed T1-weighted sequences were performed. T2-weighted sequences were repeated after the rectum was filled with ultrasonographic (US) gel. Two blinded readers interpreted images independently. Image quality was scored by using a four-point scale. Detailed mapping of deep endometriosis was performed. Colon wall infiltration was graded (none, serosa, muscularis, submucosa, mucosa). MR imaging results were compared with surgical and pathologic findings. Interobserver agreement was assessed by using kappa statistics. Nonparametric tests were performed to compare colon wall infiltration scores without and those with US gel and between observers.
Results: Twenty-seven of 41 patients had deep endometriosis at surgery and histopathologic examination. Sensitivity, specificity, positive and negative predictive values, and accuracy for the diagnosis of deep endometriosis at MR imaging were 96.3% (26 of 27), 100% (14 of 14), 100% (26 of 26), 93.3% (14 of 15), and 97.6% (40 of 41), respectively. kappa Values ranged from 0.65 to 1.0, depending on the location of deep endometriosis. Colon wall infiltration assessment by both readers correlated well with pathologic findings (Spearman coefficient, >0.93), although median wall involvement scores were lower at pathologic examination than for both readers both before (P = .042 and P = .011) and after (P = .079 and P = .011) intrarectal gel filling.
Conclusion: MR imaging of the pelvis at 3.0 T is accurate in the diagnosis and staging of deep endometriosis for the preoperative assessment of patients clinically suspected of having endometriosis.