基于体素的形态测量分析常规MRI阴性智力障碍儿童脑灰质体积的变化

A voxel-based morphometric analysis on change of gray matter volume in children with conventional MRI-negative mental retardation

目的应用基于体素的形态测量(Voxel based morphometry,VBM)技术测量常规MRI阴性智力障碍儿童脑灰质体积的改变,从脑结构水平探讨智力障碍相关机制。方法收集2017年8月至2018年11月就诊于遵义医科大学附属医院儿科中心智力障碍患儿22例为病例组,按照年龄、性别、受教育程度及利手匹配原则选择26名正常健康儿童作为对照组;所有受试者均采用高分辨率3D-T1WI脑MR扫描,运用基于SPM8的DARTEL工具箱进行VBM分析,采用独立样本t检验比较两组儿童各脑区灰质体积差异(P<0.01,FDR校正,Cluster size>50),年龄、性别、受教育程度和全脑容积为协变量。同时,对病例组的智商评分(IQ)与异常脑区灰质体积进行Pearson相关分析。结果病例组与对照组间的年龄、性别、受教育程度及全脑体积差异均无统计学意义(P>0.05)。与对照组比较,病例组灰质体积下降的脑区包括双侧海马、额上回、扣带回、右侧颞中回、左侧颞上回、海马旁回、中央前回、颞上回;Pearson相关分析显示病例组异常脑区(左侧海马)灰质体积与IQ呈正相关(r=0.638,P=0.011)。结论常规MRI阴性智力障碍儿童额叶、颞叶、海马部分功能区灰质体积缩小;且左侧海马灰质体积与儿童智力IQ存在相关性,表明海马灰质体积的减少可能是儿童智力障碍的原因之一。

Objective Voxel-based morphometric(VBM)techniques were used to measurethe changes of gray matter volumein children with conventional MRI-negative intelligence retardation.The mechanism of mental retardation was discussed from the level of brain structure.Methods A retrospective analysis of 22 children diagnosed with mental retardation at the Pediatric Center of our hospital from Aug 2017 to Nov 2018.The routine magnetic resonance examination was negative.According to the age,gender,education level and matching principle,26 healthy children were selected as the control group.The high resolution 3D T1 brain MR scans were performed and the VBM analysis was performed using the DARTEL toolbox based on SPM8.Independent sample t test was used to compare the difference of gray matter volume between the two groups(P<0.01,FDR correction,cluster size>50).Age,gender,education level,and brain volume were covariates.Meanwhile,the Pearson correlation analysis was performed on the IQ score of the case group and the gray matter volume of the abnormal brain region.Results There was no significant difference in age,gender,education level and brain volume between the case group and the healthy controls(P>0.05).Compared with the control group,the brain areas with decreased gray matter volume in the case group included bilateral hippocampus,superior frontal gyrus,cingulategyrus,right middle temporal gyrus,left superior temporal gyrus,parahippocampalgyrus,central anterior gyrus and superior temporal gyrus.Pearson correlation analysis showed that the gray matter volume in the abnormal brain(left hippocampus)area of the case group was negatively correlated with IQ(r=0.638,P=0.011).Conclusion The volume of cortical gray matter in frontal lobe,temporal lobe and hippocampus of children with normal mental retardation on conventional MRI was decreased.The change in gray volume of bilateral hippocampus reflects the degree of mental retardation in children.Hippocampal damage is one of the causes of mental retardation in children.