Multimodality Magnetic Resonance Imaging In Patients With White Matter Hyperintensity Of Vascular Origin

Part I: Tractography study in patients with white matter hyperintensity of vascular originObjective: White matter hyperintensity of vascular origin(WMH)is the most common neuroimaging finding of cerebral small vessel disease and it is associated with disruption of the microstructural integrity of white matter fibers throughout the brain.In patients with WMH,various clinical features such as hypertension,advanced age,obesity,and cognitive decline are often observed.However,whether these clinical features are associated with disrupted white matter structural connectivity in the brain requires further investigation.Therefore,in this study,we explored white matter fiber tract pathways associated with WMH based on the whole brain level,and investigated important clinical features associated with microstructural damage in white matter fiber tracts in the midbrain of WMH patients.Methods: A total of 16 patients with vasogenic cerebral WMH and 20 healthy controls(HC)were included in this study.First,clinical and general data were collected from all subjects,including overall cognitive assessment such as Montreal Cognitive Assessment(Mo CA),clinical factors highly associated with WMH such as hypertension score and body mass index(BMI),and then diffusion data were collected from all subjects using the same MR scanning protocol.The data collected were first analyzed by DSI studio(diffusion spectrum imaging studio,DSI studio)software to obtain white matter pathways with impaired global brain connectivity in the patient group,and since most scores were highly correlated with each other,principal component analysis(PCA)was then used to separate principal components that explained the variability of the overall score,and finally specific pathways of white matter tracts associated with each major component were determined.Results: The Mo CA score between the WMH and HC groups differed significantly(two-sample t-test,p<0.001);In principal component analysis,hypertension scores,Montreal Cognitive Assessment(Mo CA)scores,and body mass index(BMI)were sufficient to explain 87.196% of the score variance;The anterior splenium of the corpus callosum,inferior longitudinal fasciculus,anterior corpus callosum,and middle cerebellar peduncle were significantly associated with hypertension scores(FDR = 0.04).The anterior splenium of corpus callosum,left thalamoparietal fasciculus,inferior longitudinal fasciculus and left cerebellum were significantly correlated with Mo CA score(FDR = 0.01).The anterior splenium of the corpus callosum,fronto-occipital fasciculus,cingulate fasciculus,fornix/fimbria were significantly associated with BMI(FDR < 0.01).Conclusions: Our findings show that hypertension score,Mo CA score,and BMI are important representative clinical features involved in specific microstructural damage in WMH patients.Part II: Synthetic MRI imaging of patients with vasogenic white matter hyperintensitiesObjective: White matter hyperintensity is one of the important imaging features of subcortical vascular cognitive impairment,and the main pathological change is demyelination.However,myelin loss also exists in the white matter region adjacent to WMH.In this study,longitudinal relaxation time(T1)value,transverse relaxation time(T2)value and proton density(PD)value of synthetic magnetic resonance imaging(Sy MRI)were used to investigate myelin loss in the lesion area and white matter hyperintensity penumbra(PWMH)area of WMH patients,and to explore the relationship between relaxation time and proton density changes and cognitive function.Methods: A total of 39 patients with WMH and 20 healthy controls were included in this study.All subjects underwent general data collection,neuropsychological assessments such as the Montreal Cognitive Assessment(Mo CA),Auditory Verbal Learning Test(AVLT),Trail Making Tests A and B,and Digit Span Test,followed by Sy MRI data collection through the same MR scanning protocol.According to the synthetic T2-Flair sequence,ROI delineation was performed in the selected lesion and paralesional white matter(PMWH)of each patient,and ROI delineation was performed in the normal white matter(NAWM)of healthy controls.Corresponding values were obtained from T1,T2,and PD quantitative maps,respectively.T1,T2,PD values were compared between groups using analysis of variance(ANOVA)for the lesion group of WMH,PWMH group,and NAWM group of healthy controls.Correlation between each quantitative parameter value and cognitive score in WMH patients was assessed by Pearson or Spearman correlation analysis.Results: The total number of ROIs in 39 patients was 660: including 165 lesions,495 PWMHs,and 160 ROIs in the NAWM group of 20 healthy controls.Compared with the PWMH and HC groups,T1,T2,and PD were increased in the WMH group(P < 0.001);T2 values were significantly increased in the PWMH group compared with the NAWM group(P = 0.002);T1,T2 and PD were correlated with cognitive scores,and it was found that T2 were negatively correlated with Mo CA scores in the WMH group(r =-0.361,P = 0.024),and T2 were negatively correlated with Mo CA scores in the PWMH group(r =-0.522,P < 0.001).Conclusion: Sy MRI can provide multiple parameters to quantitatively evaluate the lesion and paralesional white matter injury in patients with WMH,and T2 values may be more sensitive than other parameters.T2 values in the white matter region adjacent to the lesion can provide valuable information for evaluating cognitive impairment in patients with WMH.