Construction And Application Of Hippocampal Morphological Network Based On Structural Magnetic Resonance

Some studies have shown that in patients with Alzheimer’s disease(AD)and temporal lobe epilepsy(TLE),hippocampus and hippocampal subfields show different atrophy and the degree of atrophy is proportional to the course of the disease.However,relevant studies only evaluated the changes of gray matter volume in the hippocampus,and did not explore the relationship between the hippocampus and other brain regions,as well as the subfields within the hippocampus.In recent years,the development of structural magnetic resonance imaging(s MRI)and the introduction of graph-based brain network analysis provide a new and effective method for the study of hippocampal morphological network in AD and TLE neurological diseases.Some studies have proposed methods for constructing hippocampal network morphological connectivity,but these methods are based on group level and can only be analyzed for a single feature.To solve this problem,we constructed a hippocampal morphology network at the individual level in this paper.In addition,we constructed a morphological network of hippocampal subfields and studied the changes of the topological structure of the morphological network of hippocampal subfields in TLE patients.The main research contents of this paper are as follows:1.Realized the construction of individual level hippocampal morphological network.In order to determine the core position of hippocampus in morphological network,Morphometry based on voxel(VBM)method was firstly used to analyze the gray matter volume of AD patients.The results showed that the abnormal gray matter volume of AD patients was mainly distributed in the right cerebellum,right hippocampus and bilateral hippocampus,especially in bilateral hippocampus.It indicates that hippocampus may be the core node in the morphological network and affect the surrounding brain regions,which provides a theoretical basis for constructing the hippocampal morphological network.In order to construct an individual level hippocampal morphological network,26 morphological features(volume features and 25 texture features)were used as feature vectors.The correlation matrix was obtained by calculating the Pearson correlation coefficient of the eigenvectors of hippocampus and other substructures.2.Achieved individual hippocampal morphological network studies in AD patients and TLE patients.The results showed that there were significant differences between AD patients and TLE patients in hippocampal morphological network and normal subjects,and significant differences in connection patterns and cognitive connections were found.The results suggested that hippocampal injury may not be limited to local areas,but may have extensive,harmful or compensatory effects on other parts of the brain,and that hippocampus and thalamus may play a key role in AD and TLE patients.3.Realized the construction and analysis of the morphological network of hippocampal subfields in patients with TLE.The volume of each subfields of hippocampus was calculated.The morphological network of the subfields of hippocampus was constructed by taking the subfields of hippocampus as the node and the Pearson correlation coefficient of the volume of the subfields as the edge.The experimental results show that the morphological network of hippocampus subfields in TLE patients is reorganized,the connection between bilateral hippocampus is weakened,the connection within hippocampus is strengthened,the core node is changed,the degree of network collectivization in TLE patients is reduced,the transmission efficiency is weakened,and the network is damaged.To sum up,firstly,in order to reduce the influence of individual differences and analyze the morphological network of hippocampus comprehensively,we constructed a morphological connection network between hippocampus and whole brain gray matter nucleus at the individual level.Secondly,the hippocampal morphological network of AD patients and TLE patients at individual level was studied.The results showed that the abnormal changes of hippocampal morphological network were found in AD patients and TLE patients.Thirdly,in order to study the functional pattern of the hippocampal subfields in TLE patients,we constructed the morphological network of the hippocampal subfields of TLE patients,and found the abnormal changes of the topological properties of the morphological network in the hippocampal subfields of TLE patients.This study provides a new perspective and theoretical basis for the pathological study of neurological diseases such as AD and TLE in the future.