联合FCD和VBM研究AD和MCI患者的脑结构和功能改变

Brain Structural and Functional Degradation Research of AD and MCI Patients Based on FCD and VBM

目的:本研究将利用基于体素形态测量学(voxel based morphometry, VBM)和基于静息态血氧水平依赖功能磁共振(blood-oxygenleveldependentf MRI,BOLD-fMRI)的功能连接密度(functional connectivity density,FCD),比较阿尔茨海默病(Alzheimer’s disease,AD)、轻度认知障碍(mild cognitive impairment,MCI)和健康老年人对照(normal control,NC)组间脑灰质体积和脑FCD的改变。方法:对19名AD患者,22名MCI患者,以及32名性别、年龄匹配的NC进行三维脑结构磁共振和BOLD-fMRI检查。采用VBM的方法分析AD、MCI、NC全脑的形态学改变。采用全脑功能连接密度(global FCD,gFCD)、短程功能连接密度(short-range FCD,sFCD)和长程功能连接密度(long-range FCD,lFCD)的方法分析AD、MCI、NC脑功能活动状态,gFCD用于分析每个体素与全脑体素的连接数量,s FCD用于分析每个体素与周围体素的连接数量,lFCD用于分析每个体素与远端体素的连接数量。利用SPM8、DPARSF、REST软件进行统计分析,采用方差分析、两样本t检验,p value<0.01差异有统计学意义。结果:AD与NC相比,双侧海马、海马旁回和左侧中央前回灰质显著萎缩(pvalue<0.01),楔前叶的sFCD显著减小(pvalue<0.01);AD与MCI相比,双侧海马及海马旁回灰质显著萎缩(p value<0.01),楔前叶的sFCD显著减小(p value<0.01);MCI与NC比较,左侧中央前回灰质显著萎缩(p value<0.01),楔前叶sFCD有减小趋势(pvalue=0.06)。AD、MCI、NC的gFCD和l FCD各组之间无显著差异。结论:本研究证实了AD和MCI患者双侧海马、海马旁回和左侧中央前回脑萎缩之外,还发现楔前叶的短程功能连接密度在患者中减低,为AD和MCI患者脑结构和功能退化的机制研究奠定了理论和方法学基础,有助于临床的早期诊断和治疗。

Objective This study will compare the changes of gray matter volume and whole brain functional connectivity density (FCD) in the brains of Alzheimer’s disease (AD), mild cognitive impairment (MCI) and healthy elderly normal control (NC) people using voxel based morphometry (VBM) and FCD based on resting-state blood-oxygen level dependent fMRI (BOLD-fMRI). Methods 19 participants diagnosed with AD, 22 participants diagnosed with MCI, and 32 NC who were matched in gender and age were recruited. Three-dimensional brain structure scans and BOLD-fMRI were performed on all participants. We evaluated whole brain changes of morphology in AD, MCI and NC using VBM. And we evaluated changes of brain functional activity in AD, MCI and NC using global FCD (gFCD), short-range FCD (sFCD) and long-range FCD (lFCD). We used gFCD for evaluating numbers of connections between one voxel and whole brain voxels. We used sFCD for evaluating numbers of connections between one voxel and short-range brain voxels. And we used lFCD for evaluating numbers of connections between one voxel and long-range brain voxels. We used SPM8、DPARSF、REST for data analysis and statistics, and we evaluated ANCOVA and two-sample t-test. The difference p value<0.01 was statistically significant. Result Compared among AD, MCI and NC, the volume of brain gray matter is significantly different in bilateral hippocampus, parahippocampal and left precentral (p value<0.01), and the sFCD is significantly different in precuneus (p value<0.01). The mean values of the brain regions were obtained: compared to NC, AD indicates significant gray matter atrophy in bilateral hippocampus, parahippocampal and left precentral (p value<0.01), and significant sFCD decreasing in precuneus (p value<0.01). Compared to MCI, AD indicates significant gray matter atrophy in bilateral hippocampus, parahippocampal (p value<0.01) and significant sFCD decreasing in precuneus (p value<0.01). Compared to NC, MCI indicates significant gray matter atrophy in left precentral (p value<0.01), and a sFCD decreasing trend in precuneus (p value=0.06). There is no significant change in gFCD and lFCD among AD, MCI and NC. Conclusion This study confirmed the AD and MCI patients with brain atrophy in bilateral hippocampal, parahippocampal gyrus and left precentral gyrus, and we also found the sFCD of precuneus decreasing in the patients. It lays a theoretical and methodological foundation for the study on the mechanism of brain structure and function degeneration in AD and MCI patients, and it is helpful for early clinical diagnosis and treatment.