| PART â… :Resting-state f MRI study of patients with ischemic white matter lesions with and without cognitive impairment using amplitude of low-frequency fluctuation analysisBackgrounds and objective:White matter lesions(WML) is a pathologic status with white matter demyelination and axonal loss mainly caused by cerebral chronic ischaemia or hypoperfusion of small vessel disease. It display white matter hyperintensities in T2-weighted or fluid attenuated inversion recovery images of MRI. The prevalence is higher than 30% in aged people over 60 years and increases with ageing. Studies have shown that WML could lead to cognitive decline and sometimes may be the key reason of dementia. However the neural mechanism of it is still unclear. Amplitude of low frequency fluctuation(ALFF) can reflect the cerebral spontaneous activity and have been used wildly in neural disease study. Until now there is no study about the relationship between ALFF change and cognitive imapirment of WML patients. So, in this study we used resting-state functional MRI to investigate the ALFF alteration and its correlation with cognitive impairment in WML patients.Materials and Methods :60 WML patients were included in this part. They were divided as WML with cognitive impairment(WML_CI) group(30 cases) and WML without cognitive impairment(WML_NCI) group(30 cases) according to cognitive performance. Thirty healthy elderly matched with age, gender and education were recruited as normal controls(NC group). All of them were scanned with fluid attenuated inversion recovery sequence, three-dimensional magnetization-prepared rapid gradient-echo imaging(3D MPRAGE) sequence and rs-f MRI using an echo-planar imaging sequence(EPI)sequence in a Siemens 3.0 T magnetic resonance imaging system. Data processing was conducted using SPM8 toolkit, DPARSF and REST software. SPSS13.0 software was used for statistical analysis of clinical data. Measurement data was analyzed with analysis of variance(ANOVA), while enumeration data was analyzed with crosstab analysis. The WML visual rating score of the WML_NCI and WML_CI groups were compared using nonparametric kolmogorov-smirnov test. Group-wise ALFF analysis was proceeded using ANOVA in REST software. The result was corrected with Alpha Sim procedure and the threshold was set as P<0.05(combined a single threshold of P<0.01 and a minimum cluster size of 18 voxels). Then the ALFF value that showed significant group differences was extracted for post hoc analyzing. Finally, the correlation between ALFF value and cognitive scores was analyzed, with age, gender and education as covariates. A threshold of P < 0.05 was considered as statistical significance.Results:1. There was no significant difference in age, gender, education and mean frame displacement among the three groups(P > 0.05). The Mo CA and MMSE scores of WML_CI group were lower than those of the NC group and WML_NCI group(P<0.001), while no difference was found between those of the NC group and WML_NCI group. The visual grading scores of white matter lesions showed no significant difference between WML_CI and WML_NCI groups(P = 0.346).2. Significant ALFF differences were found in the left middle temporal gyrus(MTG_L), left precuneus(Pcu_L), right orbital part of superior frontal gyrus(SFG_Orb_R), right superior occipital gyrus(SOG_R) and right inferior occipital gyrus(IOG_R) among the three groups(P < 0.05, Alpha Sim corrected). Compared with normal controls, WML_NCI patients showed significantly increased ALFF in the IOG_R, Pcu_L, SFG_Orb_R and SOG_R, while WML_CI group exhibited increased ALFF in the SFG_Orb_R, IOG_R, and decreased ALFF in the MTG_L. When compared to WML_NCI group, WML_CI patients showed significantly declined ALFF in the IOG_R, MTG_L, Pcu_L and SOG_R.3. With age, gender and education as covariates, the partial correlation analysis showed positive correlation between ALFF and Mo CA scores in MTG_L(r = 0.375, P = 0.031), and negative correlation between Pcu_L(r =-0.378, P = 0.031) and MMSE scores in the WML_CI patients.Conclusion:In this study, abnormal spontaneous activity was detected in WML patients. T he WML_NCI showed ALFF increasing and WML_CI dispalyed ALFF decreasing in mutiple regions. There is close correlation between cognitive impairment and spontaneous activity changes in WML patients. These results can help understand the mechanism of cognitive impairment of WML. PART â…¡: Memory deficits of patients with ischemic white matter lesions with cognitive impairment and its correlation with amplitude of low-frequency fluctuation of resting-state f MRI signalBackgrounds and Objective:Ischemic white matter lesions can cause prominent cognitive dysfunction even dementia. The cognitive impairment area include executive dysfunction, attention damage and decline of information processing, which were caused by the interruption of connectivity between basal ganglia and prefrontal lobe. Memory is the foundation of all cognition. It has been reported that ischemic white matter lesions could cause memory deficit in its early stage. However, few reports has focused on the m emory impairment features and mechanism of WML. In this study, we used auditory verbal learning test(AVLT) and amplitude of low-frequency fluctuation to investigate the memory dysfunction features of WML patients with cognitive impairment and its correlation with cerebral spontaneous activity alteration to help understand the memory impairment mechanism of WML.Materials and Methods :Fifteen patients with ischemic white matter lesions and cognitive impairment(WML_CI group) and 15 normal controls(NC group) matched with age, gender and education were included in this part. All of them underwent a detailed memory evaluation using auditory verbal learning test(AVLT). The MRI data were collected using a Siemens 3.0 T MRI scanner with fluid attenuated inversion recovery sequence, three-dimensional magnetization-prepared rapid gradient-echo imaging(3D MPRAGE) sequence and rs-f MRI using echo-planar imaging sequence. Data processing was performed with SPM8, DPARSF and REST software. The results were displayed with Brain Net Viewer and REST Slice Viewer software. Measurement data was analyzed with two sample t-test, rank-sum test and enumeration data with chi-square test. The ALFF value of the two groups was compared in REST software with gray matter volume as a covariate. The result was corrected by Alpha Sim procedure and the threshold was set as P<0.05(combined a single threshold of P<0.01 and a minimum cluster size of 18 voxels). Finally, the correlation between the ALFF value and AVLT scores was analyzed, with age and gender and education as covariates. A threshold of P < 0.05 was considered as statistical significance.Results:1. There was no significant difference in gender, age and education between the two groups(P>0.05). The Mo CA, MMSE and short-term memory(STM) scores in WML_CI groups were significant lower than those of the NC group(P<0.05). There were no significant differences in short delayed recall, long delayed recall, total score and recognition scores between the two groups(P>0.05).2. Compared with NC group, WML_CI patients exhibited decreased ALFF in left cuneus and right insula, and increased ALFF in bilateral posterior cingulate cortex, bilateral putamen, right pallidum, left medial frontal gyrus(MFG), left superior frontal gyrus(SFG) and left supplementary motor area(SMA)(P<0.01, Alpha Sim corrected).3. Removing the influence of age, gender, education, a closed negative correlation was found between ALFF value in bilateral putamen and STM scores(left: r =-0.606,P = 0.037;right: r =-0.586,P = 0.045).Conclusion:Short-term memory dysfunction is the main memory impairment features in WML_CI patients. It may be associated with the abnormal spontaneous neuronal activity of mutiple brain regions especialy bilateral putamen. |
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