Series FMRI Research Of Cerebral Metabolism And Function In T2DM Patients

Objective: Using ~1H-MRS,ALFF and graph theory to explore the abnormalities of brain metabolism of posterior cingulate cortex,the spontaneous brain activity and the topological properties of the functional networks in Type 2 diabetic patients,the thesis tries to explore the early biological markers and to discuss the possible pathological mechanism of T2DM cognitive impairment by neuroimaging.Materials and Methods: 88 subjects were recruited and divided into 3 groups according to the MoCA scores.31 belonged to T2DM group and 22 belonged to T2DM-MCI group,and 35 healthy persons were in HC group.The clinical laboratory indexes and cognitive function test were performed before MRI scan.(1)The ~1H-MRS spectra of bilateral PCC regions were collected by single voxel method.The area under NAA,Cr,Cho,mI curves was read and the ratio of NAA / Cr,Cho / Cr,mI / Cr,NAA / Cho,NAA / MI were calculated.Every two groups were compared among the three groups,and clinical laboratory indicators and cognitive function score were analyzed..(2)The three groups of subjects were collected and analyzed by DPARSF software.The changes of ALFF values in the brain of patients in the groups of T2DM and T2DM-MCI with Slow-5,Slow-4 and Slow-2 sub-frequency were analyzed.(3)BOLD-fMRI data,Gretna software and Power-264 template were employed to construct brain functional networks and compute small world properties,global efficiency(Eg),local efficiency(Eloc)and node global efficiency(node Eg).The small-world properties of the brain function of the three groups and changes of Eg,Eloc and Eg were analyzed,and the correlation between these indexes and cognitive function score was analyzed.Results:1.Compared T2DM with HC group,Cr and Cho decreased,mI increased,and NAA/ mI decreased(p<0.05).Compared T2DM-MCI with HC group,NAA and Cr decreased,mI increased,NAA/Cr、Cho/Cr、mI/Cr increased,and NAA/ mI decreased(p<0.05).Compared T2DM-MCI with T2DM group,Cho/Cr increased and NAA/mI decreased(p<0.05).Correlation analysis found that NAA and C peptide was positive correlation(r = 0.448,p = 0.448),NAA and AVLT towered positive correlation(r = 0.949,p = 0.051),and mI/Cr ratio was negatively related to the MoCA score(r =-0.957,p = 0.043).2.More aberrant spontaneous brain activities were found in Slow-5 and Slow-4 band than in Slow-2 band.The basal ganglia and precuneus were most robust in Slow-5,and the occipital lobe,cingulate corcex,SMA were detected in Slow-5 and Slow-4;frontal lobe,temporal lobe,parietal lobe,cerebellum were detected in Slow-5,Slow-4 and Slow-2,but the ALFF reducing of frontal cortex was only found in Slow-2.Compared with HC,ALFF values in right lingual and calcarine in T2DM group were decreased.However,compared with T2DM and HC group,there were more ALFF decreased cortexes but few increased cortexes in T2DM-MCI group.3.Within sparsity 0.05-0.40,the functional networks of T2DM and T2DM-MCI still kept small-world properties;Lp increased and Eg reduced,but there was no significant difference(P>0.05).Compared with HC group,node Eg was reduced in left medial prefrontal cortex,left inferior parietal lobule,left cuneus,left PCC,middle cingulum,righe postcentral gyrus,righe inferior tempral,right lingula and right fusiform,but increased in left superior temporal in T2DM group.Node Eg was reduced in left middle frontal gyrus,left inferior frontal gyrus,left inferior temporal gyrus,left ACC,left angular,left inferior parietal lobule,left middle occipital and right post central gyrus in T2DM-MCI group.Compared with T2DM group,node Eg was reduced in right middle frontal gyrus,right inferior frontal gyrus,right angular,left ACC,left middle temporal gyrus and left cebelum,but increased in left superior temporal in T2DM-MCI group.Correlation analysis showed that the Eg value of bilateral middle frontal gyrus,bilateral inferior frontal gyrus,bilateral middle temporal gyrus,bilateral inferior parietal lobule,right insula and left superior temporal was significantly positive correlated with MoCA score(FDR correction,p < 0.05).Conclusion:1.It is feasible and effective to investigate the metabolic changes and characteristics of T2DM-MCI caused by related micro injury cerebral regions by using ~1H-MRS and selected PCC.The aberrant metabolic character was marked by decrease NAA and Cr content,which represent neuronal damage and energy metabolism decreased in the PCC in T2DM-MCI patients.NAA/mI ratio is expected to become the biological indicator to evaluate T2DM cognitive impairment.2.Using sub-frequency ALFF,the abnormal activity of spontaneous neuron in brain of T2DM patients can be detected comprehensively and carefully.Moreover,the abnormal spontaneous neuronal activity regions have been distributed according to the frequency.The basal ganglia and precuneus were most robust in Slow-5;the occipital lobe,cingulate corcex,SMA were detected in Slow-5 and Slow-4;frontal lobe,temporal lobe,parietal lobe,cerebellum were detected in Slow-5,Slow-4 and Slow-2;and it is sensitive to detect the ALFF decrease of frontal cortex in Slow-2.3.The occipital gyrus and the medial prefrontal gyrus were early damaged in T2DM.With cognitive impairment aggravated,the ranges of ceberal injury regions were extended,and mainly impacted the visual network,DMN,executive control network and so on.These results suggest that the mechanism of cognitive impairment in T2DM may be a combined outcome of multisystem dysfunction in the brain.4.The functional network both in T2DM and T2DM-MCI group remain small-world properties,but the functional integration and functional differentiation are decreasing,The Eg values of the right middle frontal gyrus,inferior frontal gyrus may play a critical role in the proess from normal cognitive function to cognitive dysfunction.