Atypical Cortical Thickness and Subcortical Volumes in Cerebral Microbleed Patients: A Combined FreeSurfer and Diffusion Tensor Imaging Study

Previous neuroimaging studies have suggested that cerebral small vessel disease (SVD) can show subtle anatomical alterations in specific brain regions. We aimed to characterize structural abnormalities in cerebral microbleed (CMB) patients by combining FreeSurfer and diffusion tensor imaging. In this study, patients with mild symptoms of ischemic cerebral vascular disease underwent MRI examinations 1-2 weeks after symptom onset and were divided based on SWI sequence into two groups:CMB patients and non-CMB controls. Cortical thickness and subcortical volumes were extracted and analyzed for group differences. To avoid the confounding effects of coexisting cerebrovascular disease, age, numbers of lacunar infarcts, deep white matter hyper intensity (DWMH) and PVH scores were employed as nuisance variables in all statistical analyses. Probabilistic tractography was performed in regions of interest to investigate abnormal fiber connectivity patterns. No differences were found between CMB and control groups in global grey matter volumes. Reductions of cortical thickness were found in several cortical regions in CMB patients compared to control subjects. However, right caudate nucleus volumes were found to be larger in CMB patients compared to controls when the number of lacunar infarcts, the degree of DWMH and PVH were used as nuisance covariates. Using diffusion tensor imaging and probabilistic tractography, increased right precuneus-caudate fasciculus and right precentral-caudate fasciculus were found in CMB patients compared to controls. In summary, morphologic abnormalities were found in CMB patients in the cerebral cortex and in subcortical structures. The results suggest that cerebral cortex atrophy is associated with both the distribution of small lesions within and the volume of the caudate nucleus. These findings add to the understanding of the underlying mechanisms of CMB.