不同时期特发性脱髓鞘性视神经炎视神经扩散张量成像研究

Directional diffusivities changes of optic nerve in optic demyelinating neuritis

目的探讨不同时期特发性脱髓鞘性视神经炎(IDON)患者视神经扩散张量成像(DTI)指标的变化规律。设计前瞻性病例对照研究。研究对象35例IDON患者及与患者性别、年龄相匹配的35例健康志愿者。方法应用GE1.5T磁共振扫描仪对研究对象进行视神经DTI检查,扫描时间约10分钟,利用FMRIB软件对图像进行校正和配准,利用DTIStudio软件进行视神经DTI参数的测量,分析扩散指标变化。主要指标平均扩散率(MD)、各向异性分数(FA)、最大本征值(λ∥)和横向本征值(λ⊥)。结果与对照组相比,首次受累的急性期IDON视神经DTI指标变化以FA值降低(P=0.000)和λ⊥值升高(P=0.000)为主,缓解期IDON视神经DTI指标变化为FA值降低(P=0.000),MD值(P=0.004)、λ∥值(P=0.005)和λ⊥值升高(P=0.000)。结论磁共振成像DTI技术可敏感地检测特发性脱髓鞘性视神经炎患者视神经内的水弥散异常,并且视神经DTI指标能够反映不同时期组织的病理生理改变特点及其脱髓鞘程度。

Objectives To detect and monitor the structural changes of optic nerve caused by idiopathic demyelinating optic neuritis （IDON） by measuring the full diffusion tensor （DT）. Design Prospective case-control study. Participants 35 IDON patients and their sex-and age-matched healthy controls. Methods Diffusion tensor imagings of optic nerve were performed by GE signa 1.5T scanner system. Then eddy current distortions and motion artifacts in the DT-MRI data were corrected by applying affine alignment, using FMRIBs diffusion toolbox. The maps of MD, FA and eigenvector were calculated by using DTI Studio. Main Outcome Measures Mean diffusivity （MD）, fractional anisotropy （FA）, primary （λ∥） and transverse eigenvalue （λ⊥ ）. Results Compared with healthy controls, acute IDON patients had significant decrease in FA （P= 0.001） and significant increase in λ⊥ （P=0.001）. However, chronic IDON had significant increase in MD （P=0.004）,λ∥ （P=0.005） and λ⊥ （P=0.000） and significant decrease in FA （P=0.000）. Conclusion These results show the great potential and capacity of DT-MRI measures as very useful biomarkers and indicators for the evaluation of myelin injury in the optic nerve.