Magnetic Resonance Imaging Structural And Functional Study In Patients With Alzheimer’ Disease

PART Ⅰ Gray matter volume changes over the whole brain in Patients with aMCI and mild Alzheimer’s disease:A longitudinal Voxel-Based morphometry studyObjectiveTo study the pattern of volume changes of the whole brain gray matter in patients with amnestic mild cognitive impairment(aMCI) and mild Alzheimer’s disease(AD) by voxel-based morphometry (VBM).Material and Methods 37 patients with aMCI,30 patients with mild AD and 30 normal aging volunteers were enrolled in the study. Gray matter volume differences of the whole brain were assessed using SPM8-based toolbox to make voxel-based morphometric comparison between patients and the control group.17 patients with aMCI weregivenfollow-up examinations after one year. Results The volume of the bilateral temporal lobes、hippocampus、parahippocampal gyrus、gaudate、putamen、supramarginal、thalamus and occipital gyrus, besides,left postcentral gyrus、angular、right insula、precentral and inferior frontal lobe,etc in the aMCI patient group were significantly smaller than that in the control group. The volume of the bilateralmiddle temporal gyrus、middle frontal gyrus、superior frontal gyrus、occipital fusiform gyrus、left postcentral gyrus、 precuneous cortex、right supramarginal、precentral gyrus and central opercular cortex、superior parietal lobule、lateral occipital cortex、 inferior frontal gyrus,etc in the mild AD patients group were significantly smaller than that in the control group. The volume of therightprecuneous and lateral occipitalcortex、left inferior occipital gyrus、bilateral supramarginal gyrus、middle frontal gyrus、 left paracingulate gyrus、angular gyrus、inferior temporal gyrus、 right putamen、inferiorfrontal gyrus、superior temporal gyrus、middle occipital gyrus and brainstem, etc in the mild AD patients group were significantly smaller than that in the aMCI group (P<0.05, FDR-corrected, K>100voxels). Longitudinal cortical thinning were found in bilateral frontal、temporal、parietal and occipital lobes (P<0.05, uncorrected, Cluster>100voxels). ConclusionGray matter reductions in widespread brain observed with VBM in patients with aMCI and AD, the method may offer help to diagnosis in early stage for therapy.PART Ⅱ cerebral perfusion changes over the brain in Patients with aMCI and mild Alzheimer’s disease:A longitudinal arterial spin labeling studyObjectiveTo study the application of pulsed arterial spin labeling (PASL) technique in cerebral perfusion of patients with amnestic mild cognitiveimpairment(aMCI) and mild Alzheimer’s disease (AD). Material and Methods 37 patients with aMCI,30 patients with mild AD and 30 normal aging volunteers were enrolled in the study. Relative cerebral blood flow(rCBF)in three groups were assessed using SPM8.17 patients with aMCI weregivenfollow-up examinations after one year. Results The rCBF was higher in bilateral posterior cingulate cortex and precuneus in aMCI group than in control group. The rCBF was lower in left inferior parietal lobe、superior parietal lobe、 angular、middle frontal lobe、right superior temporal lobe in AD group than in control group. The rCBF was lower in left middle frontal lobe、 precuneus、right postcentral、inferior parietal lobe、middle frontal lobe in AD group than in aMCI group.(Alphasim corrected, p<0.05, K>1632 voxels).Bilateral hypertransfusion and hypoperfusion were found in frontal、temporal、parietal、occipital lobes and thalamus ,cingulate gyrusin longitudinal study. Higher in bilateral frontal lobes slightly (p<0.05, uncorrected, k≥100voxels). Conclusion PASL perfusion is a valuable method for detecting the abnormal perfusion changes in aMCI and AD patients, the results suggest the structural and functional changes are closely related.PARTⅢ White Matter Abnormalities in Patients with aMCI and mild Alzheimer’s disease:A longitudinal voxel-based whole brain diffusion tensor imaging studyObjectiveTo detect white matter (WM) patterns of microstructural abnormalities and better investigate the pathologic process in amnestic mild cognitiveimpairment (aMCI), mild Alzheimer’ s disease (AD) with magnetic resonance diffusion tensor imaging (DTI). Material and Methods 37 patients with aMCI,30 patients with mild AD and 30 normal aging volunteers were enrolled in the study. Fractional anisotropy (FA) maps were processed using tract-based spatial statistics (TBSS) to make voxel-based comparison of DTI parameters in whole brain between the three groups.17 patients with aMCI weregiven follow-up examinations after one year. Results Significant reduction in FA in right genu of corpus callosum、bilateral inferior fronto-occipital fasciculus、superior longitudinal fasciculus、right anterior limb of internal capsule、anterior thalamic radiation、left inferior longitudinal fasciculus were found in aMCI group;while increase in right corticospinal tract、anterior thalamic radiation、 right superior longitudinal fasciculus、cingulum(hippocampus)、 bilateral inferior fronto-occipital fasciculus、right anterior thalamic radiation、forceps majorand left superior longitudinal fasciculus.In patients with mild AD, significant reduction in FA werefound in left superior corona radiata、superior longitudinal fasciculus、bilateral inferior fronto-occipital fasciculus、right cingulum(hippocampus)、external capsule、fornix、left anterior thalamic radiation、stria terminalis、external capsule、cingulum; while increase in left corticospinal tract、anterior thalamic radiation、right superior longitudinal fasciculus、uncinate fasciculus、cingulum(hippocampus)、inferior fronto-occipital fasciculus、anterior thalamic radiation、forceps major、bilateral inferior longitudinal fasciculus、left cingulum(P<0.05,t value 2-6, FDR Corrected).Significant increase in MD in left inferior longitudinal fasciculus、uncinate fasciculus、inferior fronto-occipital fasciculus、superior longitudinal fasciculus corticospinal tract、right superior longitudinal and uncinate fasciculus were found in aMCI group,while reduction in a small part of corticospinal tract. In patients with mild AD, significant increase in MD in left superior longitudinal fasciculus、corticospinal tract were found in mild AD group,while reduction in a small part of corticospinal tract (P<0.05, FDR Corrected). Inlongitudinal study, obvious reduction in FA were found in left superior corona radiate and inferior Longitudinal fasciculus, increase in a little part of right cingulum and superior longitudinal fasciculus. Apparent increase in MD were seen in left forceps major and right cingulum, reduction ina little part of right cingulum and superior longitudinal fasciculus. (P<0.05, uncorrected,cluster>100voxels) Conclusion DTI detects changes in microstructural white matter that are regarded as prominent features of AD and thus, shows promise in its function as a diagnostic biomarker. Using the technique, we could demonstrate DTI changes at follow-up which correlated well with clinical progression, which used to monitor the disease progression and observe the treatment response.PARTⅣ Resting-state functional MRI analysis in aMCI and mild Alzheimer’ s diseaseObjective To investigate the brain activity in resting state of patients with aMCI and mild Alzheimer’s disease by ALFF and seed-based correlation analysis. Material and Methods 37 patients with aMCI,30 patients with mild AD and 30 normal aging volunteers as control subjects were scanned with 3. OT MRI. fMRI data were preprocessed with such softwares as SPM8, DPARSF and then compared between patients and the control group.17 patients with aMCI were givenfollow-up examinations after one year. Results ALFF analysis revealed activity intensity increased in right middle frontal gyrus、 superior frontal gyrus in aMCI group;decreased in right middle frontal gyrus、left precuneus、right anterior cingulate、corpus callosum、inferior frontal gyrus and precuneus (P<0.01, uncorrected, K≥10 voxels). In patients with mild AD, significant increase in ALFF were found in right corpus callosum、left premotor cortex、superior frontal gyrus、right front and side cingulate gyrus、left middle frontal gyrus.Decrease were found in right rectal gyrus、left cingulate gyrus、post cingulate gyrus、precuneus(P<0.01,uncorrected, K≥10 voxels). The compare between the two groups showed significant increase in ALFF in right supplementary motor area、frontal lobe、 left precentral gyru、paracentral lobe、cingulate gyrus、supplementary motor area、right precentral gyrus、superior frontal gyrus、left postcentral gyrus in mild AD group.Decrease were found in bilateral cerebellum、left inferior frontal gyrus、superior occipital gyrus and middle occipital gyrus(P<0.01,uncorrected,K≥10 voxels). Seed-based correlation analysis detected more activation in default mode network in aMCI group increased in bilateral precuneus and central cingulate gyrus; less activation in right temporal lobe (P<0.01, uncorrected, K≥10 voxels). In patients with mild AD, significant increase were found in left insula, frontal inferior orbitalis; less activation in bilateral frontal lobe、middle temporal lobe (P<0.01, uncorrected, K≥10 voxels). The compare between the two groups showed significant increase in right frontal superior gyrus in mild AD group. Decrease were found in right frontal lobe、anterior cingulate、central cingulate gyrus、temporal lobe、supramarginal gyrus、frontal inferior triangle、paracentral lobe (P<0.01, uncorrected, K≥10 voxels) Longitudinal ALFF decrease were found in right cerebellum and calcarine(P<0.05, FWE corrected, K≥10voxels); activation of default mode network decreased in right cerebellum, increased in right parietal inferior lobe、angular、frontal middle lobe、frontal superior lobe、left parietal inferior lobe、temporal inferior lobe、frontal middle lobe (P<0.01, uncorrected, K≥10 voxels). ConclusionALFF and seed-based correlation analysis can detect the abnormalities of resting-state brain activity before the structural alternation can be demonstrated. The combination of structural and functional analysis of the brain can reveal more information than each of them purely.