小年龄段孤独症谱系障碍的脑白质纤维束弥散张量成像研究

Diffusion tensor imaging of the white matter fasciculus in young children with autism spectrum disorders

目的：通过弥散张量成像（diffusion tensor imaging,DTI）研究小年龄段孤独症谱系障碍（autism spectrum disorders,ASD）的脑白质微结构特点。方法：16例1.5-5.6（3.2±1.4）岁ASD及10例1.5-5.7（3.4±1.4）岁正常发育儿童行DTI扫描,按照脑白质纤维束示踪图集定位纤维束,目标纤维束包括胼胝体膝部、体部及压部、双侧扣带束、双侧钩束、双侧下额枕束、双侧下纵束。每个纤维束画制2-4个感兴趣区,测量各向异性分数（fractional anisotrophy,FA）和平均弥散系数（average diffusion coefficient,ADC）。比较ASD组与正常对照组之间FA及ADC的差别。结果：ASD组胼胝体压部FA值0.66±0.07,右侧扣带束FA值0.31±0.03,分别高于正常对照组的0.58±0.09（P=0.030）和0.27±0.06（P=0.037）;ASD组胼胝体压部ADC值1.00±0.09,左侧扣带束ADC值0.84±0.04,分别低于正常对照组的1.15±0.18（P=0.015）和0.88±0.04（P=0.026）。结论：小年龄段ASD部分白质纤维束FA值升高,提示可能存在早期过度发育。

Objective：To study the microstructural features of the white matter fasciculus in young children with autism spectrum disorders（ASD） by measuring fractional anisotrophy（FA） and average diffusion coefficient（ADC） through diffusion tensor imaging（DTI）. Methods：Sixteen ASD patients aged from 1.5 to 5.6 years（mean 3.2±1.4） and 10 typical development children aged from1.5 to 5.7 years（mean 3.4±1.4） were included in this study.DTI was performed on all patients. The regions of interest（ROI） was determined according to Fiber Tract-Based Atlas of Human White Matter Anatomy by Johns Hopkins University. The ROIs included cingulum,uncinate fascicules,splenium,body and genu of corpus callosum,inferior fronto-occipital fasciculus,and inferior longitudinal fasciculus.The mean FA and ADC values were obtained by drawing 2-4 ROIs.The differences of FA and ADC between ASD patients and typical development children were statistically analyzed. Results：FA in the splenium of corpus callosum（0.66 ±0.07） and the right cingulum（0.31±0.03） were significantly higher in ASD group than in control group（0.58±0.09,P=0.030;0.27±0.06,P=0.037）.ADC in the splenium of corpus callosum（1.00 ±0.09） and the left cingulum（0.84 ±0.04） decreased significantly in ASD patients comparing with the typical development children（1.15±0.18,P=0.015;0.88±0.04,P=0.026）. Conclusion：The FA of some white matter fibers is higher in young children ASD than in the controls,suggesting that abnormal excessive development of white matter possibly exist at the early stage of ASD.