肌萎缩侧索硬化症基于体素的形态测量扩散张量分析

目的 利用基于体素的形态测量学(VBM)及基于体素的扩散张量分析评价肌萎缩侧索硬化症(ALS)患者的脑灰质、白质体积及各向异性分数(FA)值的改变.方法 选取39例确诊或拟诊为ALS的患者(ALS组)及39名健康成年人(对照组)进行常规MR扫描及神经心理学评估,并采集3D快速扰相梯度回波(fast spoiled gradient echo,FSPGR)序列T_1WI和DTI数据.对3D T_1结构像进行配准、分割、平滑后,采用VBM分析,计算分割后的脑灰质、白质及脑脊液的体积.选取76名健康志愿者进行DTI,对原始图像进行后处理,制作FA模版,将ALS组和对照组受试者的FA图配准在所创建的FA模版上,测量FA值.统计方法采用协方差分析,因性别完全匹配,故对于VBM,年龄及全脑总体积作为协变量,而对于基于体素的扩散张量分析,仅年龄作为协变量,P＜0.01(未校正),相连像素＞20个的脑区为有差异的脑区.结果 全脑体积分析显示两组受试者的全脑灰质体积、全脑白质体积、全脑体积及脑灰质分数之间差异无统计学意义,但ALS患者的白质分数(0.29±0.02)小于健康对照组(0.30±0.02)(P=0.003).与健康对照组比较,ALS患者局部灰质体积减少脑区主要位于双侧额上回及中央前回,右侧额中回及颞中、下回,左侧枕上回、楔叶及左侧岛叶,ALS患者局部白质体积减少脑区主要位于胼胝体膝部,双侧额内侧回、旁中央小叶及岛叶,右侧额上回及额中回、左侧中央后回.ALS患者双侧扣带回及海马旁回FA值较对照组减低.结论 ALS并不是单纯的运动神经元病,是一种多系统受累的疾病,基于体素的扩散张量分析对于怀疑认知功能障碍的患者海马旁回及扣带回白质FA值变化的检出具有一定的潜在价值.

Voxel-based morphometry and voxel-based diffusion tensor analysis in amyotrophic lateral sclerosis

Objective To evaluate gray matter volume,white matter volume and FA value changes in amyatrophic lateral sclerosis(ALS)patients by voxel-based morphometry(VBM)and voxel-based diffusion tensor analysis(VBDTA).Methods Thirty-nine definite or probable ALS patients diagnosed by El Escorial standard and 39 healthy controls were recruited and underwent conventional MR scans and the neuropsychological evaluation.The 3D FSPGR T_1WI and DTI data were collected on GE Medical 3.0 T MRI system.The 3D T_1 structural images were normalized,segmented and smoothed,and then VBM analysis was performed.DTI data were acquired from 76 healthy controls,and FA map template was made.FA maps generated from the DTI data of ALS patients and healthy controls were normalized to the FA map template for voxel-based analysis.ANCOVA was applied,controlling with age and total intracranial volume for VBM and age for VBDTA.A statistical threshold of P＜0.01(uncorrected)and cluster level of more than continuous 20 voxels determined significance.Results Statistical results showed no significant difference in the global volumes of gray matter and white matter,total intracranial volumes and gray matter fraction between ALS patients and healthy controls,but the white matter fraction of ALS patients(0.29±0.02)was significantly less than that of healthy controls(0.30±0.02)statistically(P=0.003).There was significant reduction of gray matter volumes in bilateral superior frontal gyri and precentral gyri,right middle frontal gyrus,right middle and inferior temporal gyrus,left superior occipital gyms and cuneus and left insula in ALS patients when compared with healthy controls;and the regional reduction of white matter volumes in ALS patients mainly located in genu of corpus callosum,bilateral medial frontal gyri,paracentral lobule and insula,right superior and middle frontal gyrus and left postcentral gyrus.VBDTA showed decrease in FA values in bilateral parahipocampal gyri and cingulate gyri in ALS patients compared with healthy controls.Conclusions VBM and VBDTA analysis results suggest that ALS is not simply a motor neuron disease but a multisystem disorder;and VBDTA has a potential value for the detection of FA value changes of cingulate and parahippocampal gyral white matter in suspected cognitive impairment of ALS patients.