Magnetic Resonance Imaging in the Evaluation of (Deep Infiltrating) Endometriosis: The Value of Diffusion-Weighted Imaging

Purpose: To assess the value of magnetic resonance (MR) diffusion-weighted imaging (DWI) in the evaluation of deep infiltrating endometriosis (DIE). Materials and Methods: In a prospective single-center study, DWI was added to the standard MRI protocol in 56 consecutive patients with known or suspected endometriosis. Endometriotic lesions as well as (functional) ovarian cysts were analyzed for location, size, and signal intensity on T1, T2, and DWI. Apparent diffusion coefficient (ADC) values were calculated using b-values of 50, 400, 800, and 1200 s/mm(2). Statistical analysis included the Spearman correlation coefficient, Mann-Whitney U, and Kruskal-Wallis tests. Results: A total of 112 lesions (62 endometrial cysts and 48 DIE) were detected, 60 of which were large enough to analyze. Mean ADC values of endometrial cysts and functional ovarian cysts were 1.11 x 10(-3)/mm(2)/s and 2.14 x 10(-3)/mm(2)/s, respectively. Mean ADC values of DIE retrocervical, infiltrating the colon, and bladder were 0.70 x 10(-3)/mm(2)/s, 0.79 x 10(-3)/mm(2)/s, and 0.76 x 10(-3)/mm(2)/s, respectively. ADC values of DIE did not show a significant difference between varying pelvic locations (P = 0.63). Conclusion: Results of our study suggest that ADC values of DIE are consistently low, without significant difference between pelvic locations.