Analysis Of The Topological Characteristics In The Brain Structural Network Of Patients With Primary Angle-closure Glaucoma Based On The Diffusion Tensor Imaging

ObjectivesTo construct and investigate the abnormalities of the topological properties of the brain structural connectome in patients with primary angle-closure glaucoma(PACG)patients using the technique of diffusion tensor imaging(DTI),with an objective to provide a new insight to understand the potential neuropathologic mechanism of this disorder.MethodsNineteen preoperative PACG patients and nineteen gender-and age-matched healthy controls(HCs)underwent MRI scans including high-resolution T1-weighted scan and DTI scan.The whole brain was parceled into 90 cortical and subcortical regions within the Automated Anatomical Labeling template.The data analysis was based on the fiber assignment by continuous tracking method.We defined the fiber number between the nodes as the weighted edge to reconstruct the brain structural network.Then the method of graph theory was utilized to analyze the network characteristics.We quantified the network properties at both global and local level.T-test was used to compare those topological properties between two groups.Spearman correlation analysis was performed to compute correlations between the topological characteristics of PACG patients and clinical parameters.In addition,the hubs in both two groups were computed and further analyzed.Results1.No significant difference was observed at the level of global properties between PACG group and HCs.The structural network in both groups had the small-world property.2.The nodal efficiency was significantly reduced in the right dorsolateral part of superior frontal gyrus,right orbital part of inferior frontal gyrus,left amygdala,left cuneus and left median cingulate and paracingulate gyri of patients with PACG.3.The nodal degree was significantly reduced in the left orbital part of superior frontal gyrus,right orbital part of inferior frontal gyrus,left amygdala,left cuneus and left lingual gyrus of patients with PACG compared with HCs.4.Two hubs which is the right middle temporal gyrus and left inferior parietal lobule were not detected in the structural network of PACG patients.5.The nodal degree of left lingual gyrus was negatively correlated with vertical cup-to-disc ratio,while positively correlated with visual acuity.The nodal degree of left amygdala was negatively correlated with visual acuity.Conclusion1.The structural network of PACG patients were constructed homogeneously,with retaining the high efficiency in the passage of information at the global level.2.Nodes with decreased nodal degree or nodal efficiency mainly located at the brain regions controlling visual,emotional or cognitive function.It is indicated that PACG is not only an ophthalmic disease but a complex brain syndrome.3.The missing states of the hubs located in the visual and emotional area indicated the existence of the reorganization in those functional modules4.The local topological properties in PACG groups were correlated with clinical parameters.The method of brain structural network construction can be regarded as an indicator to auxiliary guide the clinical diagnosis and treatment.