MRI Structural Study In Patients With Alzheimer’s Disease Based On Normal FA Template

Part1Reliable Study of Voxel-based Analysis Based on Two Different FA TemplatesObjectiveComparing the results of Voxel-based Analysis(VBA) based on two different Fractional anisotropy(FA) templates to learn more about the reliability of this method, so as to provide basic information for functional study of brain white matter and diagnosis of the related diseases.Methods27normal volunteers were recruited (divided into two group, one was the young group with14subjects, the other was the old group with13subjects) to perform diffusion tensor imaging scans. First, automatic image registration, tensor calculation were performed in DTIStudio software. Next, the FA maps acquired from the first step were coregistered, normalized and smoothed using SPM8software package. And then Voxel-based Analysis between the two groups’ FA were studied based on two FA templates separately with SPM8. The first template was the study-specific FA template produced in SPM8, the other was our self-created Chinese normal FA template. In addition, the Tract-based Spatial Statistic (TBSS) method and related literatures were applied to validate the different results from two kind of FA templates.ResultsAs to the study-specific template, compared with the young group, the old group’s white matter FA significantly decreased in bilateral anterior and posterior limbs of internal capsule, left external capsule, left superior frontal gyrus, left occipital lobe, right corona radiata, right cerebral peduncle, right middle frontal gyrus, right inferior frontal gyrus, right middle cerebellar peduncle (P<0.05, FWE corrected). Based on the normal Chinese FA template, the significantly decreased areas of FA were distributed in left posterior limb of internal capsule, left external capsule, left superior frontal gyrus, left middle temporal gyrus, left occipital lobe, right corona radiata, right anterior limb of internal capsule, right posterior limb of internal capsule, right cerebral peduncle, right middle frontal gyrus, right inferior frontal gyrus, genu of corpus callosum (P<0.05, FWE corrected). There were four different areas in the two templates. Left anterior limb of internal capsule and right middle cerebellar peduncle belonged to the first template, while left middle temporal gyrus, genu of corpus callosum shown up on the second template. From the active areas of TBSS, we could conclude that both left anterior limb of internal capsule and right middle cerebellar peduncle were false positive. The results of TBSS and related literatures were mostly in accordance with those in our Chinese mormal FA template.ConclusionsWhen it comes to voxel-based analysis of brain white matter, our self-created Chinese normal FA template may play an important role in improving the objectivity and reliability of the results. Part2Voxel-Based Study of Brain White Matter in Alzheimer’s DiseaseObjectiveUsing MRI to investigating the pattern of white matter atrophy and microscopic change of white matter in the same individual brains with AD, in order to provide a neuroimaging indicator for the early auxiliary diagnosis of AD patients.MethodsAfter approved,13AD subjects’ DTI and T1image were downloaded from ADNI database. And13normal old people with similar age as control group were recruited to perform T1WI and DTI scans. First, the preprocessing of T1image were performed using VBM8toolbox. White matter volume differences of the whole brain between the two groups were assessed using SPM8software package. Next, automatic image registration, tensor calculation of all DTI images were performed in DTIStudio software. The FA maps acquired from the previous step were coregistered, normalized and smoothed using SPM8based on our self-created normal FA template. And voxel-based analysis between the two groups’ FA were studied.ResultsThe white matter volume of the bilateral occipital lobe, temporal lobe, lenticular nucleus, hippocampus, left parietal lobe, left cerebellar vermis and right posterior cingulate in the AD patient group was significantly smaller than that in the control group(p<0.001, k≥90voxels). Based on the normal FA template, compared with the control group, the AD group’s white matter FA significantly decreased in bilateral fornixes, splenium and posterior part of corpus callosum, middle cerebellar peduncle, left superior longitudinal fasciculus, left frontal lobe, left temporal lobe and left thalamus.(P<0.001, k≥5voxels).ConclusionsVBM and VBA of FA based on normal Chinese FA template can reveal widespread reduction of white matter in AD with the advantage of objectivity.