| Objective:In a seemingly resting state,the activity of internal neurons changes rapidly.Dynamic functional connection takes into account the fluctuation of functional connection in a shorter time range,which can better reflect the dynamic changes of internal information interaction in the brain than static functional connection.Based on resting functional magnetic resonance(rs-f MRI)data,dynamic and static Regional Homogeneity(Re Ho),ROI brain network connection difference and large-scale network connection analysis were used to explore the differences of dynamic and static functional connections in patients with cerebral small vessel disease(CSVD)and the brain functional changes of different degrees of cognitive impairment in CSVD patients.Methods: Collect CSVD patients who visited the Department of Neurology of the affiliated Hospital of Southwest Medical University from October 2019 to December 2020,and recruited healthy volunteers openly in the hospital.Through the selection of inclusion criteria and exclusion criteria,a total of 46 subjects were included in 27 healthy elderly volunteers(healthy elderly group)and 19 CSVD patients(CSVD group).The subjects’ general demographic data,including height,age,weight and years of education,were collected,and their MMSE and Mo CA scores were evaluated by professionals.After completion,the subjects were guided to complete the MRI data acquisition.The acquisition sequence includes T1 sequence and resting state EPI sequence(10 minutes).The f MRI data are preprocessed,and then the following aspects are studied: 1.To study the difference of static Re Ho and dynamic Re Ho and the difference of ROI brain network connection between the patients with CSVD and the healthy elderly group.2.The differences of largescale brain functional network connections between patients with CSVD and healthy elderly groups were compared.3.According to the actual situation of the sample,the patients with CSVD were divided into high group and low group,and the difference of large-scale network connection in CSVD group was analyzed.Results: 1.Comparison of general data: there was no significant difference in age,sex and education level between CSVD group and healthy elderly group,but there was significant difference in MMSE and Mo Ca scores.Comparison of static Re Ho and dynamic Re Ho between 2.CSVD group and healthy elderly group: the activities of static Re Ho and dynamic Re Ho were highly consistent,and the differences between the two groups were concentrated in the cerebellum.After strict voxel level < 0.01 and cluster level P < 0.05 and double tail GRF correction,the results of static Re Ho analysis were as follows: the difference between CSVD group and healthy elderly group was mainly distributed in left cerebellar Crus2 area(BA20),right cerebellar Crus2 area(BA27),right cerebellar area 7b(BA12),right cerebellar area 8(BA8).For dynamic Re Ho analysis,the results were as follows: the difference between CSVD group and healthy elderly group was mainly distributed in left cerebellar Crus2 area(BA8),left cerebellar Crus1 area(BA67),right cerebellar Crus2area(BA55),right cerebellar Crus7 b area(BA17).The difference of ROI network connections between the 3.CSVD group and the healthy elderly group:compared with the healthy elderly group,the direct functional connections of several cerebellar subregions such as bilateral Crus2,bilateral Crus1,bilateral7 b,left 6 and multiple frontal lobe subregions such as right dorsolateral superior frontal gyrus(Frontal＿Sup＿R),middle frontal gyrus(Frontal＿Mid＿R)and medial superior frontal gyrus(Frontal＿Sup＿Medial＿R)were significantly decreased.Comparison of large-scale network connections between the4.CSVD group and the healthy elderly group: the biggest difference in the brain network between the two groups was mainly reflected in the subcortical network,that is,the frontal parietal network and subcortical network,dorsal attention network and subcortical network were different between the CSVD group and the healthy elderly group,and the difference was statistically significant(P < 0.05).For other average intra-network connections and internetwork connections,no significant differences were found.Subgroup analysis of patients in 5.CSVD group: according to the actual situation of the sample,patients with CSVD were divided into two subgroups: high score(Mo Ca score≥ 20)and low score(Mo Ca score < 19),and their large-scale network connections were compared.The average intra-network connections of sensory/ somatic motor network,auditory network,visual network,dorsal attention network and cerebellar network were significantly enhanced in the subgroup with high Mo Ca score,that is,the group with lower cognitive impairment.There are also significant differences in the connection between the two subgroups.The average internetwork connections of low Mo Ca scores between sensory / somatic motor network and cerebellar network,banded tegmental network and cerebellar network,auditory network and cerebellar network,ventral attention network and cerebellar network,visual network and cerebellar network,frontoparietal control network and cerebellar network,subcortical network and cerebellar network decreased significantly.At the same time,other average internetwork connections such as sensory / somatic motor network and banded tegmental network,sensory / somatic motor network and auditory network,sensory / somatic motor network and ventral attention network were also significantly decreased in patients with CSVD disease(low Mo Ca score).In addition,the average network connections between banded tegmental network and auditory network,banded tectal network and ventral attention network,auditory network and ventral attention network,auditory network and frontoparietal area control network,ventral attention network and frontoparietal control network,visual network and prominence network were also significantly stronger in the high Mo Ca score subgroup than in the low Mo Ca score subgroup.Conclusion:In this study,based on rs-f MRI data,Re Ho differential brain regions were analyzed between CSVD patients and healthy elderly groups.it was found that the static and dynamic Re Ho differences between the two groups were in the cerebellum,suggesting that there were abnormal changes in cerebellar activity in CSVD patients,which may be related to the decline of their cognitive function.In the analysis of ROI brain network,it was found that the connection between cerebellum and frontal lobe was significantly decreased in CSVD patients,which may be the brain network mechanism of cognitive decline in CSVD patients.In the analysis of large-scale network connection,it is found that the abnormal change of network connection is mainly reflected in the increase of the average connection between the subcortical network,the frontoparietal network and the dorsal attention network,which may be a kind of compensation.In the subgroup analysis of CSVD group,it was found that compared with those CSVD patients with severe cognitive impairment(Mo Ca score < 19),CSVD patients with mild cognitive impairment(Mo Ca score ≥20)had enhanced average intra-network and inter-network connections.This large-scale change in the brain network seems to be able to assess the severity of CSVD lesions to some extent.It not only provides a new perspective for the study of the mechanism of cognitive impairment in patients with CSVD,but also provides a new way to study the network plasticity caused by pathological changes. |
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