急性颈髓外伤的DTI临床应用

The clinical application of diffusion tensor imaging in acute cervical spinal cord trauma

目的:探讨磁共振扩散张量成像(DTI)在急性颈髓外伤中的临床应用价值。方法:41例急性颈髓外伤(外伤后3天内)患者行常规MRI、DTI和扩散张量纤维束成像(DTT)检查。41例患者按照常规T2WI上有无异常信号,分为阳性组(17例)和阴性组(24例);选取年龄、性别相匹配的15例健康人作为对照组。分析各组中表观扩散系数(ADC)、各向异性分数(FA)、平行于颈髓长轴、前后径和左右径的本征值(λ1、λ2、λ3)的变化。结果:与对照组比较,颈髓外伤患者的FA值均降低,T2WI阳性组中ADC、λ2、λ3均增高,而T2WI阴性组中λ3值升高,差异均有统计学意义(P<0.05)。与T2WI阴性组比较,阳性组中λ3值较高,FA值较低,差异有统计学意义(P<0.05)。DTT图显示颈髓损伤处神经纤维有不同程度的稀疏、移位、扭曲及断裂等征象。结论:FA、λ3值是检测颈髓外伤早期颈髓微结构改变的敏感指标,纤维束图能直观显示纤维束的细微变化情况。

Objective：To investigate the clinical application value of MR diffusion tensor imaging （DTI）in acute cer-vical spinal cord trauma.Methods：41 patient with acute cervical spinal cord trauma within three days after the trauma under-went conventional MRI and DTI examination.All the subjects were divided into positive group （n= 17）and negative group （n= 24）,according to the conventional T2-weighted imaging.In addition,15 healthy volunteers were recruited as the control group with the matched age and sex.ADC,FA,λ1 ,λ2 andλ3 values were then calculated,and the fiber tracking of the cervi-cal cords was obtained.Results：Compared with the control group,FA value was significantly decreased in the patients with the cervical spinal cord trauma;the values of ADC,λ1 andλ2 were significantly increased in the T2-weighted positive group of the cervical spinal cord trauma;λ3 value was significantly increased in the T2-weighted negative group （all P〈0.05）. Compared with the T2-weighted negative group,the T2-weighted positive group had significantly higherλ3 value and lower FA value （both P〈0.05）.Diffusion tensor tractography （DTT）images demonstrated the different degrees of displace-ment,porosis,distortion and brack of the fibers of the injured cervical spinal cords.Conclusion：Both FA andλ3 value are sensitive indicators in detecting the subtle changes of the microstructures in the early stage of the cervical spinal cord trau-ma.The fiber tracking can visually display the subtle changes of the nerve fibers.