[Disruption of corpus callosum microstructural integrity by diffusion MRI as a predictor of progression of cerebral microangiopathy]. / Narushenie mikrostrukturnoi tselostnosti mozolistogo tela po dannym diffuzionnoi MRT kak prediktor progressirovaniya tserebral'noi mikroangiopatii.

OBJECTIVE: To assess the microstructural integrity of the corpus callosum in patients with cerebral small vessel disease (cSVD) using signal and biophysical diffusion MRI models and to identify the most sensitive markers of disease progression. MATERIAL AND METHODS: Diffusion MRI (3 Tesla) was performed in 166 patients (51.8% women; mean age 60.4±7.6) with cSVD and cognitive impairment of varying severity and in 44 healthy volunteers (65.9% women; mean age 59.6±6.8), followed by calculation of signal (diffusion tensor and diffusion kurtosis) and biophysical (WMTI, NODDI, MC-SMT) models, from which profiles of three corpus callosum segments were constructed. RESULTS: The best results were obtained for metrics in the forceps minor and body of the corpus callosum. Among the metrics of the signal models in the forceps minor, fraction anisotropy (FA) and mean diffusion (MD), which characterize the overall loss of microstructural integrity and increase in extra-axonal water, as well as indirect markers of demyelination when considering transverse diffusion parameters (radial diffusion and radial kurtosis), had the larger area under the curve according to the ROC analysis. Among the metrics of the biophysical models in the forceps minor, a larger area under the curve was found in the MC-SMT model for extra-axonal transverse diffusion (ETR), mean diffusion (EMD), and intra-axonal water fraction (INTRA), and in the WMTI model for intra-axonal water fraction (AWF). ETR had high inverse correlations with INTRA and AWF, while INTRA and AWF had high direct intercorrelations. CONCLUSION: Metrics of signaling (FA, MD, RD, RK) and biophysical patterns (ETR, EMD, INTRA, AWF) in the forceps minor and the corpus callosum body can be considered as indicators of cSVD progression. They indicate disease progression, mainly by an increase in extra-axonal water with the development of demyelination and tissue degeneration in the corpus callosum.

[Predictors and integrative index of severity of cognitive disorders in cerebral microangiopathy]. / Prediktory i integrativnyi pokazatel' tyazhesti kognitivnykh rasstroistv pri tserebral'noi mikroangiopatii.

OBJECTIVE: To search for sensitive predictors of cognitive impairment (CI) and an integrative index of their severity. MATERIAL AND METHODS: We assessed CI and diffusion-tensor MRI (DT-MRI) in the regions of interest (ROI) significant for CI in 74 patients (48 women, mean age 60.6±6.9 years) with cerebral small vessel disease (CSVD). The results of DT-MRI were used to construct a predictive model of CI using binary logistic regression and to calculate an integrative index of CI severity. RESULTS: According to the constructed model, the predictors of CI were axial diffusivity (AD) of posterior frontal periventricular normal-appearing white matter (pvNAWM), right middle cingulum bundle (CB) and mid-posterior corpus callosum (CC). ROC analysis showed strong model predictive power for CI in cSVD (AUC (95% CI): 0.845 (0.740-0.950)). The threshold value of the AD predictors model for CI in cSVD was 0.53 (sensitivity 84%, specificity 76%). AD predictors of CI showed significant correlations with white matter hyperintensities volume and MoCA scores. The presence of CI as measured by neuropsychological testing and regression equation solution was corresponded to individual AD predictors of patients exceeding the CI model's threshold. CONCLUSION: Disturbances in the AD of pvNAWM, right middle CB and mid-posterior CC associated with axonal damage are a predominant factor in the development of CI in CSVD. The predictors of CI and the integrative index of CI severity calculated on their basis can potentially be used as a tool for assessing the severity of CI and the effectiveness of treatment, as well as in clarifying the interaction between vascular and degenerative pathology and in developing measures for the prevention of CI in patients with MRI signs of cSVD.