A Voxel Based Analysis Of The Correlation Of Resting-state Functional Abormal And Corresponding White Matter Abnormal In Alzheimer’s Disease

Objective:To investigate the relationship between brain activity alterations and white matter alterations in AD patients, by diffusion tensor imaging, blood oxygenation level dependent resting-state functional magnetic resonance imaging(BOLD rs-fMRI) and voxel-based analysis.Method:21AD patients and44normal cognitive elderly subjects were enrolled in the study voluntarily with informed consent. Diffusion tensor imaging was performed with EPI based sequence and32-channel head coils. Apparent diffusion coefficients(ADC) and fractional anisotropy(FA) images were calculated, normalized to the same MNI space and smoothed with8mm Gaussian Kernel. With statistical parameter mapping software SPM5package, independent two sample t-test with general linear model were performed to detect ADC and FA difference between AD patients and normal aging controls, correlation analysis was performed between MMSE score and FA, ADC with voxel-thresholded p≤0.001and cluster-thresholded P≤0.05.BOLD EPI data were obtained during resting-state using32-channel head coil, which were realigned, normalized and then smoothed with8mm FWHM kernel. Then Resting-state fMRI toolkit was used to generate ALFF and FALFF images. Independent two sample test was performed between AD and NC controls basing general linear model by statistical parameter mapping software SPM5. The significance level was set to be uncorrected0.001on the voxel level and0.05on the cluster level.Result: AD patients showed elevated ADC value and decreased FA value in bilateral temporal lobe and anterior cingulate, which was more pronounced in the left temporal lobe. There was elevation of ADC value but no FA decrease in bilateral posterior cingulate. The abnormal ADC area was larger than that of FA. There was negative correlation between MMSE score and ADC value of the right hippocampus(cluster corrected p≤0.001) and a tendency towards positive correlation between MMSE score and FA of the right hippocampus(cluster corrected p>0.05). AD patients showed elevated ALFF in left temporal lobe and right cingulated cortex(P=0.009,P=0.013), weakened FALFF in bilateral posterior cingulated cortex(P=0.002) and elevated FALFF in bilateral temporal lobes(P=0.000, P=0.023), more prominent in the left side.Conclusion:Multiple white matter regions was involved in AD patients, ADC value was more sensitive than FA value for early detection of AD patients. Right temporal lobe microstructure involvement is less severe, but has a stronger relationship with neuropsychological abnormalities. White matter injury was more severity in left temporal lobe, but cortical activity was prior in left temporal lobe consistently, AD patients showed elevated resting-state functional MRI changes in the left temporal lobe consistently, indicating left temporal lobe is the best candidate for early diagnosis and follow-up of AD patients by means of rs-fMRI, and white matter micro-structure injury and brain activity increase is causal relationship between each other in AD patients.