Micro Structural White Matter Lesion In Alzheimer’s Disease:a Diffusion Tensor Imaging Study Using Voxel-based Analysis

Objective:Alzheimer’s disease (AD) is a progressive neurodegenerative disease which is the most prevalent cause of cognitive decline in the world. The microscopic changes of white matter were more and more recognized in pathology.Diffusion tensor imaging (DTI) was employed to evaluate the changes of white matter integrity in vivo. By using a scalar value fractional anisotropy (FA), voxel-based analysis of DTI can analysis of these changes in white matter fully and accurately.At the same time, to understand the relationship between white matter changes and cognitive impairment in AD, we analyzed the correlation between FA and scores of MMSE which is contributed to detect AD and diagnose AD in clinical works.Methods:37 patients with probable AD, and 32 age-controlled cognitively normal controls(NC) were recruited from the First Affiliated Hospital of Dalian Medical University. They were all applied by detailed history taking, neuropsychological examination, MMSE and MoCA scores. All subjects underwent a conventional MRI scanning at 3.0 T, as well as a diffusion tensor imaging. First, we processed the native images to format images. Then, we performed DTI studio with the data to evaluate the value of FA changes. Analyses were run on SPM8 software and located by the Montreal Neurological Institute (MNI) coordinates. Meanwhile, we tried investigate the correlations between the two groups.Results:1. In a comparison between AD and normal controls, the scores of MMSE and MoCA were all decline sharply in AD patients(all P< 10-3).2. The AD group showed significant FA reduction in the right side of frontal lobe, temporal lobe, occipital lobe, thalamus and both sides of cingulum, corpus callosum, precuneus, inferior parietal lobule, supramaginal gyrus and parahippocampal gyrus(P<0.001,uncorrected). We can find that the FA of right cingulum(as well as ventral cingulate gyrus and Posterior cingulate cortex), left corpus callosum(including the anterior and body corpus callosum), left inferior temporal gyrus and followed by the both sides of inferior parietal lobule, inferior patieto gyrus and precuneus were significantly decreased than that in the health control groups. (P<0.05, FWE corrected)3. The results showed that there was positive correlation between the value of FA and MMSE scores. FA values in both sides of precuneus,left occipital lobe,frontal gurus and superior parietal lobe showed these significant correlations. (P<0.001,uncorrected)Conclutions:1. The scores of MMSE and MoCA can be used for analysing general cognitive function quantitative in patients with AD. Moreover, they can also be able to assess the severity of disease.2. In a comparison between AD and normal controls, FA was significantly reduced in the right cingulum,left corpus callosum, inferior temporal gyrus and followed by the both sides of inferior parietal lobule, inferior patieto gyrus and precuneus, that maybe the results from Wallerian degneration and retrogenesis.3. FA valus in both sides of precuneus,left occipital lobe,frontal gurus and superior parietal lobe showed positive correlations with the performance of MMSE, which has small clusters and locate in the region of superior longitudinal fasciculus dispersive.These changes were associated with higher neurologic impairments.4. Voxel-based analysis of DTI can analysis of changes in white matter fully and accurately, which can help to detect AD and diagnose AD in clinical works.