DIFFUSION TENSOR MAGNETIC RESONANCE IMAGING IN EARLY DIAGNOSIS OF STRUCTURAL CHANGES IN BRAIN WHITE MATTER IN SMALL VESSEL DISEASE ASSOCIATED WITH ARTERIAL HYPERTENSION AND IONIZING RADIATION

Abstract

Objective. to determine the early signs of structural changes in brain white matter in small vessel disease associated with arterial hypertension and exposure to ionizing radiation using DTI-MRI. Materials and methods. 45 patients (mean age (57.56 ± 6.34) years) with small vessel disease (SVD) associated with arterial hypertension (AH) were examined: group I – 20 patients, participants of liquidation of the accident at the Chornobyl nuclear power plant (Chornobyl clean-up workers); group II – 25 patients not exposed to ionizing radiation. MRI was performed on an Ingenia 3T tomograph («Philips»). The fractional anisotropy (FA) was determined in the main associative and commissural pathways, periventricular prefrontal areas (fasciculus fronto-occipitalis superior / anterior – f. FO ant., corona radiata anterior – CR ant.) and semioval centers (SC). Results. No signs of cerebral cortex or brain white matter (WM) atrophy, intracerebral microhemorrhages, and widespread areas of leukoaraiosis consolidation were observed in the examined patients. In the Chornobyl clean-up workers a larger number of foci of subcortical leukoaraiosis was visualized (80 %) on MRI images including multiple – 8 (40 %), > 0.5 cm – 10 (50 %), with signs of consolidation – 5 (25 %). The results of the FA analysis in semioval centers showed its significant decrease in the patients of groups I and II (p < 0,007), regardless of the presence or absence of visual signs of subcortical leukoaraiosis (ScLA) (III gr.: 253–317, p < 0.00001; IV gr.: 287– 375, p < 0.001). FA indicators in f. FO ant. and CR ant. in the patients of groups I and II differed insignificantly but were substantially lower than controls (p < 0.05). FA was significantly lower, compared to reference levels, in visually unchanged f. FO ant. (0.389–0.425; p = 0.015) and CR ant. (0.335–0.403; p = 0.05). In patients with AH-associated SVD of middle age, regardless of the effects of ionizing radiation, no significant changes in FA in the main WM associative and commissural pathways were found (p > 0.05). Conclusions. DTI-MRI allows to detect early signs of structural changes in the white matter of the brain – a significant decrease in fractional anisotropy indicators in visually unchanged periventricular and subcortical areas. The main associative and commissural pathways of the brain remain intact in the absence of widespread consolidated foci of leukoaraiosis and lacunar infarctions. The negative impact of ionizing radiation on the course of SVD associated with arterial hypertension is manifested by more active processes of WM disorganization: the prevalence and tendency to the consolidation of periventricular and subcortical leukoaraiosis foci, a significant FA decrease in semioval centers. Key words: DTI, MRI, fractional anisotropy, arterial hypertension, small vessel disease, white matter of the brain, ionizing radiation. Key words: cirrhosis, hepatobiliary system, clean-up workers of Chornobyl NPP accident, retrospective study.