Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins Hospital, Baltimore, MD 21287, USA.
AJR Am J Roentgenol. 2012 Apr;198(4):W357-64. doi: 10.2214/AJR.11.6981.
The sciatic nerve may normally exhibit mild T2 hyperintensity in MR neurography (MRN) images, rendering assessment of sciatic neuropathy difficult. The purpose of this case-control study was to evaluate whether a quantitative and qualitative analysis of the sciatic nerves and regional skeletal muscles increases the accuracy of MRN in detecting sciatic neuropathy.
We retrospectively reviewed the MRN studies of the pelvis and thighs of 34 subjects (12 men and 22 women; mean [± SD] age, 50 ± 15 years), of which 17 had a final diagnosis of sciatic neuropathy according to electrodiagnostic or surgical confirmation, and 17 had no evidence of sciatic neuropathy and served as control subjects. On each side, the sciatic nerves were evaluated for signal intensity (SI), size, course, and fascicular shape, whereas the regional skeletal muscles were evaluated for edema, fatty replacement, and atrophy. In addition, the nerve-to-vessel SI ratio was registered for each side at the same time and 8 months later.
The sciatic nerves of the abnormal sides exhibited higher nerve-to-vessel SI ratios and higher incidences of T2 hyperintensity, enlargement, and abnormal fascicular shape compared to the nerves of the normal sides. The regional muscles of the abnormal sides demonstrated a higher grade of fatty infiltration and higher frequencies of edema and atrophy. A cutoff value of nerve-to-vessel SI ratio of 0.89 exhibited high sensitivity and specificity in predicting sciatic neuropathy. Calculation of the nerve-to-vessel SI ratio demonstrated excellent inter- and intraobserver reliability.
Both qualitative and quantitative criteria should be used to suggest the MRN diagnosis of sciatic neuropathy.
在磁共振神经成像（MRN）图像中，坐骨神经通常可表现出轻度 T2 高信号，这使得坐骨神经病的评估变得困难。本病例对照研究的目的是评估对坐骨神经和区域性骨骼肌进行定量和定性分析是否会提高 MRN 检测坐骨神经病的准确性。
我们回顾性分析了 34 例受试者（12 名男性，22 名女性；平均[±标准差]年龄 50 ± 15 岁）的骨盆和大腿部的 MRN 研究，其中 17 例根据电诊断或手术证实最终诊断为坐骨神经病，17 例无坐骨神经病证据作为对照组。对每侧坐骨神经进行信号强度（SI）、大小、走行和束状形态的评估，对区域性骨骼肌进行水肿、脂肪替代和萎缩的评估。此外，在同一时间和 8 个月后对每侧记录神经与血管的 SI 比值。
与正常侧相比，异常侧的坐骨神经具有更高的神经与血管 SI 比值，更高的 T2 高信号、增粗和异常束状形态的发生率。异常侧的区域性肌肉显示出更高程度的脂肪浸润，水肿和萎缩的频率更高。神经与血管 SI 比值的截断值为 0.89 时，对预测坐骨神经病具有较高的灵敏度和特异性。神经与血管 SI 比值的计算具有很好的观察者间和观察者内可靠性。
应使用定性和定量标准来提示 MRN 对坐骨神经病的诊断。
