核磁共振眼外肌与同侧脑白质信号强度比值对甲状腺相关性眼病活动性评判价值的研究

The value of the signal intensity ratio of the extraocular muscle and the ipsilateral white matter of the MRI inthe evaluation of the activity of thyroid-associated ophthalmopathy

目的探讨核磁共振眼外肌与同侧脑白质信号强度比值（signal intensity ratio，SIR）在甲状腺相关性眼病（thyroid-associated ophthalmopathy，TAO）活动性评判中的定量价值。 方法回顾性收集符合纳入标准的甲状腺相关性眼病患者129例，共245只患眼，作为TAO组；同期无TAO的初诊Graves病患者10例，共20只眼，为GD组；正常对照32例，64只眼，为正常对照组（normal control，NC）。对上述对象行眼眶磁共振成像，测量眼外肌信号强度及同侧脑白质信号强度作为主要观察指标，同时测量眼球突出度、眼球内侧脂肪厚度等作为次要观察指标。 结果TAO组SIR、眼球内侧脂肪厚度、眼球突出度均高于GD组及NC组[1.71（1.40, 2.10）对1.26（1.22，1.34）、1.23（1.14，1.32），8.04（6.70，8.71）mm对6.16（4.86，7.08）mm、6.93（6.41，7.65）mm，20.10（18.56，22.15）mm对15.40（14.87，16.60）mm、14.73（13.40，16.07）mm，均P〈0.05]。根据眼眶正常组的SIR，以正态分布法建立正常眼外肌95%SIR参考范围为〈1.37。在上述129例患者中，有55例合106只患眼进行了临床活动性评分（clinical activity score，CAS）。将这批患眼根据CAS分为活动期（CAS≥3）与非活动期（CAS〈3）进行分析，发现两组基线临床资料基本一致，但活动期组SIR、眼球突出度均高于非活动期组[1.70（1.45，2.33）对1.41（1.25，1.75），（20.38±2.40）mm对（19.05±3.70）mm，均P〈0.05]，眼球内侧脂肪厚度两组间比较则无显著性差异（P〉0.05）。Spearman相关分析显示患者SIR值与CAS成正相关（r＝0.580，P＝0.000）。利用受试者工作特征曲线（receiver operating characteristic curve，ROC）方法，得出SIR≥1.56时判断TAO处于活动期的诊断效能最优，其敏感度为65.6%，特异性为89.1%（曲线下面积＝0.815，P＝0.000）。 结论核磁共振检测的眼外肌与同侧脑白质信号强度比值作为一种定量客观指标，能够早期对TAO患者进行活动性判别，临床推广价值强。并有利于疗效对比，联合临床常用的CAS评分，将一定程度地改善TAO的及时诊治。

Objective To investigate the quantitative value of the signal intensity ratio of extraocular muscle and ipsilateral white matter measured by MRI for the evaluation of activity in thyroid-associated ophthalmopathy. Methods A total of 129 patients and 245 eyeballs with thyroid-associated ophthahnopathy were enrolled in this study and tiffs 245 eyeballs were set as thyroid-associated ophthalmopathy group（ TAO group）. There were 10 patients with newly diagnosed Graves＇ disease and in the same period and these 20 eyeballs were set as graves＇ disease group （ GD group）. 32 nolnal people from annual physical test excluded thyroid and eye diseases and their 64 eyes were selected randomly for the normal control group （ NC group）. The signal intensity of the extraocular muscle and the ipsilateral white matter on the MRI images were measured, while did exophthalmos and the width of the inner fat of eyeballs （FWs） measurements in the same time. Results SIR, FWs, and exophthalmos of TAO group were higher than those of the other 2 groups [ SIRs ： 1.71 （1.40,2.10） vs 1.26 （ 1.22,1.34 ） and 1.23 （ 1.14,1.32 ） ; FWs ： 8.04 （ 6.70, 8.71 ） mm vs 6. 16 （4.86,7.08） mm and 6.93 （6.41,7.65） mm, exophthalmos ： 20.10 （18.56,22. 15 ） mm vs 15.40 （ 14.87,16.60 ）mm and 14.73 （ 13.40,16.07 ） ram, all P〈0.05 ]. The reference value of SIR establishing based on SIRs of NC group is less than 1.37. In total 129 TAO patients, 55 patients（ with 106 eyeballs） have a clinical activity score（CAS）. Then, these eyeballs were grouped to activity and non-activity （ grouped by CAS〉~3 ） , and thebaseline group difference of these 2 groups was not statistically significant. The SIRs and exophthalmos of activity group were higher than the non-activity group [ SIRs ： 1. 70 （ 1. 45,2.33 ） vs 1.41 （1. 25, 1, 75 ） ; exophthalmos ： （20.38 ± 2.40） mm vs （ 19.05 ± 3.70） mm, all P〈0.05 ]. But the difference of FWs of these two groups was not statistically significant （P〉0.05）. The SIRs and CAS had a positive correlation （r =-0. 580, P =-0. 000）, through the receiver operating characteristic curve （ ROC ） we get the best diagnostic performance of TAO activity when the SIR 〉 1.56（sensibility=65.6%, specificity=89.1%, AUC--0.815, P=0.000）. Conclusion The signalintensity ratio of extraocular muscle and ipsilateral white matter may discriminate the activity of TAO early as a quantitative indicator, reflecting its efficacy, and is worth clinically generalizing.