探讨磁共振3D-T₂WI-FFE（three-dimensional T₂-weighted fast field echo）序列结合曲面重组观察直肠癌放疗对骶神经形态的影响，并初步探讨其临床意义。

顺序收集2019年11月至2022年5月间北京大学首钢医院胃肠外科收治的直肠癌患者19人，平均放疗次数（23.26±4.27）次，放射剂量16~54 Gy。同时收集健康志愿者26人。均使用飞利浦Ingenia 1.5TX磁共振机行盆腔扫描，包括T₁WI轴位、T₂W-3D-FFE序列冠状位扫描。将2组扫描所得原始数据在工作站中应用曲面重建技术（CPR）对骶神经神经重建，并根据骶神经成像质量进行评级计分。对2组骶神经评级计分、骶神经信号强度、梨状肌信号强度及两者对比噪声比CNR采用独立样本t检验。

3D-T₂-FFE序列原始数据经过曲面重组后，骶神经呈高信号的条索结构，周围肌肉骨骼呈低信号，骶神经与周围组织对比清晰。2组间骶1神经、骶2神经及骶3神经评分均有统计学差异。2组间神经信号强度没有明显统计学差异（χ²=1.978，P=0.051），2组间梨状肌信号强度有统计学差异（χ²=6.77，P＜0.05），2组间骶神经与邻近梨状肌的对比噪声比有统计学差异（χ²=-3.78，P＜0.05）。

磁共振3D-T₂-FFE 序列结合曲面重组技术，可直观、准确的显示出骶神经，并可显示放射治疗后骶神经形态的改变，为临床进一步制定手术方案或评价疗效提供影像学依据。

To investigate the effect of radiotherapy on sacral nerve morphology in patients with rectal cancer using the three-dimensional T₂-weighted fast field echo (3D-T₂WI-FFE) sequence combined with curved planar reformation, and to explore its clinical significance.

From November 2019 to May 2022, 19 patients with rectal cancer were enrolled at the Department of Gastrointestinal Surgery of Peking University Shougang Hospital. The average number of radiotherapy sessions was 23.26±4.27, and the radiation dose was 16~54 Gy. At the same time, 26 healthy volunteers were collected. Pelvic scans were performed with a Philips Ingenia 1.5TX magnetic resonance machine, including T₁WI axial scan and T₂W-3D-FFE coronal scan. The original data obtained from the two sets of scans were used in the workstation to reconstruct the sacral nerve using curved planar reformation (CPR), and the score was graded according to the imaging quality of the sacral nerve. The scores of sacral nerve rating, sacral nerve signal intensity, piriform muscle signal intensity, and the contrast noise ratio (CNR) of the two groups were compared by the t-test.

After the original data of 3D-T₂-FFE sequence were reconstructed by curved planar reformation, the sacral nerve exhibited a high signal strip structure, the surrounding musculoskeletal tissues had a low signal, and the sacral nerve and surrounding tissues were clearly contrasted. There were statistical differences between the two groups in the scores of the first, second, and third sacral nerves. There was no significant difference in nerve signal intensity between the two groups (χ²=1.978, P=0.051). There was a statistical difference in the signal intensity of the piriformis muscle between the two groups (χ²=6.77, P＜0.05). The CNR of the sacral nerve and adjacent piriformis muscle also differed significantly between the two groups (χ²=-3.78, P＜0.05).

3D-T₂-FFE sequence combined with curved planar reformation technology can directly and accurately display the sacral nerve, and can display the changes of sacral nerve morphology after radiotherapy, which provides a basis for further clinical planning and evaluation of therapeutic effects.