The Study Of Patients With Early AD About Brain Structure Network Topology Property Based On MRI

Alzheimer’s disease(AD) is a kind of nervous system degenerative disease which is characterized by a progressive decline in memory and other cognitive functions,it is the most common cause of dementia.Mild cognitive impairment(MCI) is a transition state between normal ageing and dementia,and it contains two type: amnestic MCI and non-amnestic MCI,the former chief complaint with memory impairment,it is considered to be early AD,about 80% aMCI patients will develop into AD within six years,the conversion rate is about 10%~15% every year. In recent years,some brain structure and function of the network researches based on structural magnetic resonance imaging(sMRI)、functional magnetic resonance imaging(fMRI) and magnetoencephalogram(MEG) find that large scale changes of small-world property in brain network has accurred in the aMCI stage.Due to non-invasive and easy maneuverability,Diffusion tensor imaging(DTI) has been widely used in AD research, among it,fractional anisotropy(FA) and mean diffusivity(MD) are the most common parameters which will be used.The study found aMCI stage has emerged axon loss,myelin degeneration of white matter damage,manifested as the decreased FA and rised MD.But there is rarely researchs on the network of white matter in patients with aMCI.To more accurately describe the extent of white matter fiber damage,this study use FA and the number of fibers to build brain network matrix,aimed at investigating the differences of brain network topology between patients and healthy controls,to provide a reference for early diagnosis and pathophysiological mechanism of AD.This study collected brain magnetic resonance DTI data from normal subjects and patients with aMCI.Then used MRI data processing software such as SPM and PANDA to do data preprocessing and fiber tracking.finally,we constructed the brain sructure of the network.To analysis the network,we use graph theory knowledge to do the network topology characterization analysis,aimed at extracting parameters as a characteristic indicator for early diagnosis of AD.And finally we used statistical test methods to test the results of the analysis.Finally, the present study constructed DTI brain structure of the network, found parameters as as a characteristic indicator for early diagnosis of AD and used statistical test methods permutation test to verify that the parameter values have statistical significance, From the radiological aspects,we provides some help and support to early diagnosis and research in the pathophysiological mechanism of AD.