视神经脊髓炎患者视神经扩散张量成像研究

Study of optic nerve in patients with neuromyelitis optica using diffusion tensor imaging

目的探讨DTI在视神经脊髓炎（NMO）患者视神经病变中的诊断价值。方法选取28例NMO患者和38名健康志愿者进行视神经DTI扫描，并对视神经眶内段前部、中部及后部进行各向异性分数（FA值）测量。将NMO患者根据视力是否受损及视觉诱发电位（VEP）是否异常分为单眼受累组（10只眼）、双眼受累组（36只眼）及看似正常组（10只眼），所有患者进行扩展残疾状况量表（EDSS）评分。采用单因素方差分析、ROC曲线分析及Spearman相关分析，对各组间FA值及FA值与病程、EDSS评分等的相关性进行分析。结果各组间FA值比较差异有统计学意义（F=43.54，P〈0．01）。其中，单眼受累组（0．29±0．08）、双眼受累组（0．27±0．08）及看似正常组视神经（0．35±0．13）FA值较正常对照组（0．45±0．07）减低，差异均有统计学意义（P值均〈0．01），双眼受累组FA值较看似正常组FA值减低（P〈0．01）。ROC曲线分析显示正常对照组与单眼受累组、双眼受累组、看似正常组以及全部NMO患者组曲线下面积分别为0．92、0．95、0．74及0．91，其诊断视神经受损的敏感度分别为80％、86％、50％及79％，特异度均为95％。相关性分析显示FA值与NMO患者各组EDSS评分均无相关性，FA值与双眼受累组病程呈负相关（r=-0．371，P〈0．05）。结论NMO患者视神经均存在不同程度的损害，视神经DTI可以简单有效地定量评估NMO患者视神经的损害。

Objective To explore the diagnostic value of optic diffusion tensor imaging （DTI） in detecting the impairment of optic nerve in neuromyelitis optiea （NMO） patients. Methods Conventional MRI and optic DTI were performed in 28 NMO patients and 38 normal controls （NC）. Fractional anisotropy （FA） values were measured in the anterior part, middle part and posterior part of intraorbital segment of optic nerve. The patients were classified into 3 groups based on the impairment of vision and visual evoked potential （VEP）： monocular impairment （MI） group, 10 eyes; biocular impairment （BI） group, 36 eyes; and normal-appearing （NA） group, 10 eyes. All patients were performed with the evaluation of expanded disability status scale （EDSS）. One-way analysis of variance （ANOVA）, receiver operating characteristic （ROC） curve, and Spearman correlation analysis were performed among the subgroups of NMO and normal controls. Results There was significantly statistical difference between the four groups （ F = 43.54, P 〈 0. 01 ）. Decreased FA values were demonstrated in the MI group （0. 29 ±0. 08）, BI group （0. 27 ±0. 08）, and NA group （0. 35 ± 0. 13 ） compared with NC （0. 45 ± 0. 07） （P 〈 0. 01 ）. FA value in BI group was significantly lower than that of NA group（P 〈0.01 ）. Area under curve by ROC analysis in NC vs MI, NC vs BI, NC vs NA, and NC vs NMO was 0.92, 0.95, 0.74, and 0.91, respectively. The diagnostic sensitivity of ROC was 80% , 86%, 50% , and 79%, respectively. The diagnostic specificity of ROC was 95% for the each compared groups. FA value showed no correlation with EDSS for each NMO groups, and showed negative correlation with disease duration for BI group （ r = - 0. 371, P 〈 0.05 ）. Conclusions Various degrees of optic nerve injuries, indicated by decreased FA value, are present in NMO patients, andoptic DTI may be a simple and effective tool for the quantitative evaluation of optic nerve in NMO patients.