Cerebral Microbleeds Are Associated with Loss of White Matter Integrity.

BACKGROUND AND PURPOSE: Previous studies have shown that diffusion tensor imaging suggests a diffuse loss of white matter integrity in people with white matter hyperintensities or lacunes. The purpose of this study was to investigate whether the presence of cerebral microbleeds and their distribution are related to the integrity of white matter microstructures. MATERIALS AND METHODS: The study comprised 982 participants who underwent brain MR imaging to determine microbleed status. The cross-sectional relation between microbleeds and the microstructural integrity of the white matter was assessed by 2 statistical methods: a multilinear regression model based on the average DTI parameters of normal-appearing white matter and Tract-Based Spatial Statistics analysis, a tract-based voxelwise analysis. Fiber tractography was used to spatially describe the microstructural abnormalities along WM tracts containing a cerebral microbleed. RESULTS: The presence of cerebral microbleeds was associated with lower mean fractional anisotropy and higher mean diffusivity, axial diffusivity, and radial diffusivity, and the association remained when cardiovascular risk factors and cerebral small-vessel disease markers were further adjusted. Tract-Based Spatial Statistics analysis indicated strictly lobar cerebral microbleeds associated with lower fractional anisotropy, higher mean diffusivity, and higher radial diffusivity in the internal capsule and corpus callosum after adjusting other cerebral small-vessel disease markers, while only a few voxels remained associated with deep cerebral microbleeds. Diffusion abnormalities gradients along WM tracts containing a cerebral microbleed were not found in fiber tractography analysis. CONCLUSIONS: Cerebral microbleeds are associated with widely distributed changes in white matter, despite their focal appearance on SWI.

[Prevalence and risk factors of perivascular space in the population of Shunyi Study].

Objective: To investigate the prevalence on imaging, topographic distribution and risk factors of perivascular space (PVS) in community population. Methods: This study was based on the population of Shunyi Study in China from June 2013 to September 2016. One thousand two hundred and thirty-two stroke free participants older than 35 years, who completed cerebral MRI, were included. Cardiovascular risk factors were assessed by interview, physical examination and blood sample tests. PVS were evaluated on high-resolution 3-dimensional-T1WI, T2WI and FLAIR sequences. On T1WI, PVS were detected according to 3D imaging criteria. The number and anatomic location of large PVS (≥3 mm) were recorded. And severity of PVS was then semiquantitatively graded in both white matter (WM) and basal ganglia (BG). Associations between risk factors and PVS were analyzed by multinominal Logistic regression models and adjusted for age, gender and relevant confounders. Results: Perivascular spaces were observed in the BG or WM in every subject, aged (55±10) years and 37.3% male. Large PVS were detected in 19.0% (460/1 232) of participants. Severity of PVS was found to be strongly associated with age in both basal ganglia (severe versus mild: OR=1.81; 95%CI 1.45-2.27, P<0.01) and white matter (OR=1.39; 95%CI 1.13-1.71, P<0.01), and the proportion of subjects with hypercholesterolemia decreased with the severity of PVS in BG (OR=0.58, P=0.01) . The present of large PVS was found to be associated with age(present versus absent: OR=1.03, 95%CI 1.02-1.05, P<0.01) and ApoE ε4 carrier genotype(OR=1.53, 95%CI 1.01-2.23, P=0.04). Conclusions: Perivascular spaces are always detected in the BG or WM in elderly people, and large PVS are also prevalent in community-based population. The risk factors are different due to distribution and size, and may depend on anatomic or pathologic characteristics.