多发性硬化患者脑灰质损害的MRI表现及扩散张量成像定量研究

Magnetic resonance imaging and diffusion tensor imaging of gray matter damage in multiple sclerosis

目的分析多发性硬化（MS）患者脑灰质病灶的MRI特征及表现正常的脑灰质（NAGM）是否存在隐匿性损伤。方法对34例临床确诊的MS患者（MS组）和25名健康志愿者（对照组）行常规头颅MRI和扩散张量成像（DTI），观察MS的脑灰质病灶特征，测量深部灰质核团的平均扩散率（ADC）和各向异性分数（FA），采用非配对t检验比较两组间是否存在差异。结果MR检查发现MS的脑灰质病灶共83个，占全部病灶（443个）的18．7％。分布以额叶最多，其次是颞叶与丘脑。大多数病灶呈圆形或类圆形，其中T1WI发现灰质病灶60个，液体衰减反转恢复（FLAIR）序列T2WI发现病灶78个，其中71个病灶呈高或稍高信号，3个病灶呈中心低、周围稍高的环形改变，4个呈低信号。扩散加权成像（DWI）发现高信号或低信号病灶36个，其中有9个小病灶在DWI呈明显高信号。其余病灶呈等信号而不能被发现。MS组尾状核头、壳核、丘脑的ADC值分别为（8．0±0．7）、（7．4±0．5）、（7．7±0．4）×10^-4mm^2／s，均高于对照组[分别为（7．4±0．6）、（7．0±0．5）、（7．2±0．7）×10^-4mm^2／s]，差异具有统计学意义（t值分别为-3．079、-2．554、-2．722，P值均〈0．05）。结论MS的脑灰质病灶在常规MRI和DWI上的表现有一定的特征，FLAIR联合DWI可提高病灶的检出，DTI可以反映出NAGM内的隐匿性损害。

Objective To study MRI characteristics of the gray matter lesions in multiple sclerosis （MS） patients, and to investigate the occult damage in normal appearing gray matter （NAGM） by quantitative analysis using diffusion tensor imaging （ DTI ）. Methods Conventional brain MRI and DTI were performed in 34 clinically defined MS patients and 25 non-MS healthy volunteers. Main signs of the GM lesions detected by conventional MRI were analyzed, including the distribution, numbers, shape, size, signal intensity and enhanced pattern. The apparent diffusion coefficient （ADC） and fractional anisotropy （FA） values derived by DTI were measured in normal appearing deep gray matter for all participants and the differences between the two groups were compared. Results MRI examination revealed 83 lesions in cerebral gray matter, 18.7% of the total 443 lesions. The GM lesions distributed over all brain lobes especially in frontal lobe, temporal lobe, and thalamus. Thirty-four, 60, 78, and 36 plaques were detected on T1WI, TEWI, FLAIR, and reconstructed DWI images, respectively. Nine small lesions were identified on DWI more easily than on T2WI and FALIR. The ADC values of the head of caudatum （8.0 ± 0. 7） × 10^-4mm^2/s, t= -3.079, P〈0.05）, putamen （7.4±0.5） × 10^-4mm^2/s, t= -2.564, P〈0.05）, and thalamus （7.7 ± 0.4） × 10^-4mm^2/s, t = - 2. 722, P 〈 0. 05 ） in MS group were significantly higher than those in healthy controls [ the ADC values of head of caudatum （7.4 ± 0. 6） × 10^-4mm^2/s, putamen （7.0 ±0.5） × 10^-4mm^2/s,and thalamus（7.2 ±0. 7） × 10^-4mm^2/s. Conclusions This study confirms the presence of GM damage in MS. It shows MRI characteristics of the macro-lesions, and combination of FLAIR and DWI can improve the detection of GM lesions. Occult micro-change in NAGM can be evaluated by using DTI quantitative analysis.