MRI弥散张量成像在腰骶神经根受压的诊断价值初探

Diagnostic value of diffusion tensor imaging in lumbosacral nerve root entrapment

目的探讨MRI弥散张量成像(diffusion tensor imaging,DTI)对腰骶神经根受压患者的诊断价值。方法选择慢性腰背痛伴单侧下肢放射痛患者7例,健康志愿者8例,行常规MR检查及DTI横轴位扫描。常规MR检查包括T2WI、T1WI矢状位扫描、T2WI横轴位扫描,在DTI图像测量神经根各项异性分数(fractional anisotropy,FA)值,并利用专用后处理软件,采用设置感兴趣区的方法进行腰骶部神经根纤维束成像。结果健康志愿者2侧神经根的FA值分别为0.314±0.021(左L3)、0.305±0.018(右L3)、0.343±0.055(左L4)、0.330±0.055(右L4)、0.347±0.016(左L5)、0.338±0.028(右L5)、0.338±0.027(左S1)、0.343±0.032(右S1),同一节段的左右2侧FA值差异无统计学意义。纤维束成像可清晰显示所有受试者的神经根走行。7例患者共有9个受压神经根,受压神经根的FA值低于未受压神经根的FA值,所有患者的受压神经根侧别均与症状侧别一致,而常规MR检查与症状的相关性则较差。结论与常规MRI相比,纤维束成像更能反映出导致患者临床症状的受压神经根情况。

Objective To evaluate the diagnostic value of diffusion tensor imaging （DTI） in lumbosacral nerve root entrapment. Methods Seven patients with back pain and single sciatica and eight healthy volunteers underwent 3T MR imaging. The MR protocol consisted of sagittal Tl-and T2-weighted spin echo sequence, followed by an axial T2-weighted spin echo sequence focused on the lumbar disc. In all subjects, DTI was performed with echo-planar imaging and the lumbosaeral nerve roots were visualized with fiber tractography. Fractional anisotropy （FA） values in the lumbar nerve roots were quantified on DTI images. Results Respectively, mean FA values of the roots of healthy volunteers was 0. 314 ± 0. 021 （ left L3 ）, 0. 305 ±0. 018 （ right L3 ）, 0. 343± 0. 055 （ left L4 ）, 0. 330 ± 0. 055 （ right IA）, 0. 347 ± 0. 016 （ left L5 ）, 0. 338 ± 0. 028 （ right L5 ）, 0. 338 ± 0. 027 （ left S1 ）, 0. 343 ± 0. 032 （ right S1 ）. Statistically significant differences were not found between the left and right side nerve roots at the same lumbosacral segment. In all subjects, the lumbar nerve roots were clearly visualized with fiber tractography. There were nine entrapped roots in seven patients. FA values were lower in entrapped roots than in intact roots. The side of the entrapped roots shown on fiber tractography image was consistent to the symptom, while conventional MR imaging was not. Compared with conventional MR imaging, diffusion tensor imaging fiber tractography was a better tool to evaluate lumbosaeral nerve root related to the symptom.