目的：观察和探讨磁共振脊髓造影（MRM）和选择性激励技术（PROSET）序列对腰骶神经根变异（LSNRA）的显示价值及其影像表现。方法：采用常规MRI序列、3D MRM及3D PROSET序列扫描108例腰腿痛患者，MRM及PROSET序列所得图像均行3D最大密度投影重建（3D-MIP）；结合原始图像及3D-MIP图像观察双侧腰骶神经根的解剖形态及走行方向。结果：在获得优良图像的105例病例中，MRM、PROSET序列分别发现LSNRA 7例和14例，发现率分别为6.67%和13.33%，两者差异具有显著性（χ2=5.143，P=0.016）；而常规MRI序列仅发现LSNRA 3例，发现率仅为2.86%。所发现的14例变异中，Ⅱ型变异10例，占71.43％，其中Ⅱ-1型4例，占28.57%，Ⅱ-2、Ⅱ-3、Ⅱ-4型各2例，各占14.29%；Ⅲ型及Ⅵ型变异各2例，各占14.29%。结论：PROSET序列对硬膜外神经根变异的显示明显优于MRM序列，为硬膜外LSNRA的诊断提供了一种全新的方法。

Objective: To explore the application value and findings of MR myelogram(MRM) sequence and PROSET sequence in the detection of lumbosacral nerve root anomalies(LSNRA). Materials and Methods: Conventional MRI, 3D MRM and 3D PROSET sequences were performed in lumbosacral nerve roots of 108 cases with low back pain. 3D maximum intensity projection(3D-MIP) reconstruction was used in PROSET and MRM sequences. The lumbosacral nerve roots were observed in the raw images and 3D-MIP images. Results: In the 105 cases with high-quality images, LSNRA were found in the 7, 14 cases with MRM and PROSET sequence. The detection rate was 6.67% and 13.33% respectively. There were statistically significant differences between MRM and PROSET sequence(χ2=5.143, P=0.016). LSNRA were found in only 3 cases with the conventional MRI sequence. Among the 14 cases with variation, there were 10 cases of type Ⅱ(71.43%), which was composed of 4 cases of type Ⅱ-1(28.57%) and each of the type Ⅱ-2, Ⅱ-3 and Ⅱ-4 had 2 cases(14.29% each). There were 2 cases of type Ⅲ, 2 cases of type Ⅵ(14.29% each). Conclusion: PROSET sequence was superior to the MRM sequence in the detection of extradural LSNRA. So it is a good method for the diagnosis of extradural LSNRA.