3T MRI腰骶部脊神经根扩散张量成像在腰椎间盘突出症中的应用价值

目的 探索扩散张量成像(diffusion tensor imaging,DTI)和纤维示踪成像(fibre tracking,FT)显示腰骶脊神经根的可行性,并评估椎间盘突出症患者L4及L5脊神经根各向异性分数(fractional anisotropy,FA)和表观扩散系数(apparent diffusion coefficient,ADC)值的差别.方法 20例由于后外侧或椎间孔椎间盘突出引起单侧坐骨神经痛的患者和20例健康志愿者纳入研究.所有检查均在Philips Achieve 3.0 T TX MRI上进行,纤维示踪成像参数:FA阈值＝0.15;最小纤维束长度=10mm;最大角度=27°.应用横轴位T2解剖融合图像序列评估重建图像的相关性.对所有被检者的L4、L5和S1脊神经根行扩散张量和纤维示踪成像,并在FA图和ADC图上测量L4和L5脊神经根的平均FA值和ADC值.结果 腰椎间盘突出症患者和健康志愿者腰骶部脊神经根纤维束成像在T2解剖融合图像上完全匹配.在纤维示踪图像上可以清晰地辨别腰骶部脊神经根受压位置.所有患者和健康志愿者的FA值和ADC值可以从FA图和ADC图上获得.受压侧脊神经根的FA值显著低于对侧神经根(P＜0.01)和健康志愿者的(P＜0.01); ADC值显著高于对侧神经根(P＜0.01)和健康志愿者的(P＜0.01).结论 3T MRI腰骶部脊神经根扩散张量和纤维示踪成像是可行的.腰椎间盘突出症患者受压L4和L5脊神经根的FA值和ADC值有显著性的变化.

3T MRI diffusion tensor imaging of lumbosacral nerve roots in disc herniation

Objective The goal of this study is to demonstrate the feasibility of diffusion tensor imaging with fibre tracking in the lumbosaeral spinal nerve roots, and to assess potential differences in fractional anisotropy （FA） and apparent diffusion coefficient （ADC） of L4 and L5 spinal nerve roots between disc herniation and healthy disc. Methods Twenty patients with unilateral sciatica related to posterolateral or foraminal disc herniation and 20 healthy volunteers were enrolled in our study. All examinations were performed on Achieve 3.0 T TX MRI scanner （Philips Medical Systems, The Netherlands）. The following parameters were used for fibre tracking： Minimum FA= 0.15; Minimum fibre length= 10 mm; Angle Change （deg）= 27. We used the anatomical fusion with the axial T2 sequences to estimate the relevance of our reconstructions. DTI with fibre tracking of the L4, L5 and S1 spinal nerve roots was performed. Mean fractional anisotropy （FA） and apparent diffusion coefficient （ADC） values were calculated from fractional anisotropy and apparent diffusion coefficient maps. Results The tractography fibre bundle perfectly matched the lumbosacral spinal nerve roots on the T2 anatomical fusion images in patients and volunteers. Lumbosacral spinal nerve roots compression sites could be clearly identified on the tractography images. FA and ADC values could be obtained from fractional anisotropy and apparent diffusion coefficient maps in all patients and healthy volunteers. The mean FA value of the compressed spinal nerve roots was significantly lower than the FA of the contralateral nerve roots （ P 〈0.01） and volunteer＇s nerve roots （ P 〈0.01）. ADC was significantly higher in compressed nerve roots than that in the contralateral nerve root （ P 〈0.01） and volunteer＇s nerve roots （ P 〈0.01）. Conclusion 3 T MRI DTI and fibre tracking of the lumbosacral spinal nerve roots is possible. There are significant changes in FA and ADC values in the compressed L4, and L5 spinal nerve roots.