Abstract: Objective　To explore the clinical value of magnetic resonance（MR） principle of selective excitation technique（PROSET） and diffusion tensor imaging（DTI） technique in evaluating L4-S1 unilateral lumbosacral nerve root compression caused by lumbar disc herniation（LDH） locationally and quantitatively.Methods　We enrolled 20 cases of unilateral nerve root compression within L4-S1 innervation area due to LDH diagnosed clinically and treated in Jilin City People's Hospital in 2015.MR PROSET and DTI were performed for localizing the three regions of interest（ROI） respectively at preganglionic nerve root sheath out of dural sac，the ganglion and the anterior branch of the postganglionic nerve expenditure at the external orifice of the intervertebral foramen，and measuring fractional anisotropy（FA） and apparent diffusion coefficient（ADC） value.Meanwhile，diffusion tensor tractography（DTT） was also applied to observe the bilateral L4-S1 nerve roots.Results　There were totally 25 herniated discs among the 20 LDH patients（28 unilateral nerve root compression），including 22 lateral side types（22 unilateral nerve root compression） and 3 intraforaminal types（6 unilateral nerve root compression）．The features of PROSET of each type of LDH：the intraforaminal type showed that the nucleus pulposus pushed the ipsilateral epistatic nerve root outward and upward，and pushed the inferior nerve root inward slightly，while nucleus pulposus only pushed the ipsilateral inferior nerve root inward and backward in lateral side type of LDH.DTT of lumbosacral nerve plexus showed that tract sparsity，narrowing and abrupt break of compressed side nerve root were displayed in all the cases.On the same level of L4-S1 nerve roots，ADC value was significantly higher in the compressed side compared to the normal side nerve root（P<0.05）；the FA value was significantly lower in the compressed side compared to the normal side nerve root（P<0.05）．On the same nerve root，the difference among the three levels was statistically significant（P<0.05）．Conclusion　PROSET，DTI and FT could be used to evaluate the lumbosacral nerve root compression syndrome and locationally and quantitatively assess compressed nerve roots in patients with LDH.

Key words: Intervertebral disc displacement, Radiculopathy, Magnetic resonance imaging, Diffusion tensor imaging

摘要： 目的　探讨磁共振（MR）选择性激励技术（PROSET）和弥散张量成像（DTI）技术定位及定量评价腰椎间盘突出（LDH）致单侧腰骶神经根压迫症的临床应用价值。方法　选取2015年吉林市人民医院收治的临床专科检查诊断为LDH致单侧L4~S1神经支配区域神经根压迫症患者20例，行PROSET、DTI检查，取感兴趣区域（ROI）节前神经根鞘硬膜囊出行处、神经节、节后脊神经前支出椎间孔外口处3个解剖水平，测量并比较其各向异性分数（FA）、表观弥散系数（ADC）值，同时进行双侧L4~S1神经根弥散张量纤维束示踪成像（DTT）。结果　PROSET图像特征表现：20例患者共计25个椎间盘突出，28根单侧神经根受压，其中22个侧旁型突出椎间盘致22根神经根受压，主要向内后推移同侧下位神经根，不累及同节段神经根；3个椎间孔型突出椎间盘致6根神经根受压，同侧同节段神经根向外上推移，下位神经根稍向内侧推移。DTT图像显示患者患侧神经根神经纤维束出现节段性稀疏、变窄、截断等现象。患者患侧的节前神经根鞘硬膜囊出行处、神经节、节后脊神经前支出椎间孔外口处FA值低于健侧，ADC值高于健侧（P<0.05）；患者患、健侧的节前神经根鞘硬膜囊出行处、神经节、节后脊神经前支出椎间孔外口处FA、ADC值比较，差异有统计学意义（P<0.05）。结论　PROSET结合DTI、DTT对诊断LDH致单侧腰骶神经根压迫症以及定位、定量评价病变神经根有一定的临床意义。

关键词: 椎间盘移位, 神经根病, 磁共振成像, 弥散张量成像