骶丛及邻近坐骨神经MR成像技术优化探讨

MR optimal technique for imaging sacral plexus and adjacent sciatic nerve

目的 探讨骶丛及邻近坐骨神经的MR优化成像方法及其临床应用价值。方法 对20 例健康志愿者及7 例坐骨神经继发病变患者行骶丛及邻近坐骨神经的二维自旋回波(2D SE)序列T1WI和快速自旋回波抑脂(FSE F/S)序列T2WI的斜矢状位成像,轴位三维快速平衡稳态进动(3D FIESTA)序列成像并多平面重建,其中10例志愿者加做单侧斜位3D FIESTA序列成像, 7例患者平扫后行Gd DTPA增强扫描。对比正常组2D SE T1WI斜矢状位与轴位3D FIESTA序列多平面重建对骶1神经(S1)及邻近坐骨神经的显示率。运用四等级评分标准方法评价两种采集方式的3D FIESTA多平面重建对骶丛各支神经的显示程度并进行统计学分析。结果 正常志愿者中2D SE 序列与3D FIESTA序列对S1 及邻近坐骨神经显示率分别为70%和95%(P<0.01)。轴位与斜位3D FIESTA对腰骶干(LST)及S1 的显示能力有显著性差异(二者分别为P<0.01,P<0.05),对S2 及S3 的显示程度无显著性差异。病例组通过多平面重建可明确骶丛各支神经及邻近坐骨神经受累情况。结论 3D FIESTA序列通过重建可分别显示骶丛各支神经,对S1 及邻近坐骨神经的显示率明显高于2D SE序列,单侧斜位采集优于轴位采集。

Objective To study the MR optimal technique for demonstrating sacral plexus (SP) and adjacent sciatic nerves (SN) as well as its clinical value. Methods The SPs and adjacent SNs of 20 volunteers and 7 patients were imaged by GE-Signa CV/I 1.5 T MR scanner with the sequences of 2-dimension spin echo (2D-SE) T1WI, fast spin echo fat saturation (FSE F/S )T2WI oblique sagittal imaging,axial 3-dimension fast imaging employing steady state acquisition (3D-FIESTA), and additional oblique 3D-FIESTA in 10 of the 20 volunteers. The displaying rate of sacral(S_1) nerves and adjacent SNs were compared between 2D-SE T1WI and reconstructive images of axial 3D-FIESTA. The displaying degree of SPs and adjacent SNs on reconstructive images of axial and oblique 3D-FIESTA was graded, and average scores were analyzed with Wilcoxon signed rank tests. Results The displaying rates of S_1 and adjacent SN were significantly different between 2D-SE and 3D-FIESTA ( P <0.01). Oblique 3D-FIESTA was superior to axial 3D-FIESTA for demonstrating LST and S_1, but there was no significant difference in S_2 and S_3. Sacral nerves of the 7 patients were invaded and/or displaced. Conclusion Reconstructive images of 3D-FIESTA is better than 2D-SE for demonstrating of S_1 and adjacent SN, and can display every sacral nerve. Oblique acquisition is better than axial one.