Evaluation of the sacral nerve plexus in pelvic endometriosis by three‐dimensional MR neurography

Purpose To investigate the feasibility of three‐dimensional MR neurography (3D MRN) for the sacral plexus using sampling perfection with application‐optimized contrasts using different flip angle evolution (SPACE) sequences, and to demonstrate structural abnormalities in the pelvic nerve of women with pelvic endometriosis. Materials and Methods Twenty patients with pelvic endometriosis and 20 healthy controls were examined by contrast‐enhanced 3D short time inversion recovery T2‐weighted imaging (CE 3D STIR T2WI) SPACE sequences on 3 Tesla MRI. Image quality and diagnostic confidence of the sequences in identifying abnormalities of the sacral plexus were analyzed and compared with conventional three‐plane images of 2D turbo‐spin echo T2‐weighted images (2D TSE T2WI). The changes in the sacral plexus caused by endometrial lesions were evaluated. Results The sacral plexus was clearly revealed in both healthy controls and patients with endometriosis on 3D STIR SPACE images. A good agreement was reached in the evaluation of both imaging quality (Kappa value [κ] = 0.73–1.00) and diagnostic confidence (κ = 0.66–0.81) when compared between the two independent readers. Abnormalities caused by endometriosis were identified in 17 patients, unilaterally in 10 patients, and bilaterally in 7 patients. Nerve fiber abnormalities of lumbar 5 (L5) were detected in 11 patients, of sacral 1 (S1) in 14 patients and of sacral 2 (S2) in 9 patients. Conclusion CE 3D STIR SPACE sequences demonstrate its significant capacity to investigate and map the sacral plexus, and reveal the compression and adhesion of the sacral plexus nerve as a result of ectopic lesions. Level of Evidence: 3 J. Magn. Reson. Imaging 2017;45:1225–1231