Microbleeds, lacunar infarcts, white matter lesions and cerebrovascular reactivity -- a 7 T study.

The underlying pathology of lacunar infarcts, white matter lesions and also of microbleeds is poorly understood. We assessed whether the presence of lacunar infarcts, white matter lesions or microbleeds on MRI was associated with a decrease in cerebrovascular reactivity, and assessed whether this association was similar for lacunar infarcts, white matter lesions and microbleeds. BOLD-fMRI scan with breath-holding at 7 T and anatomical scans at 1.5 T were available in 49 patients with atherosclerotic disease from the Second Manifestations of ARTerial disease (SMART) study. Microbleeds and lacunar infarcts were scored visually and volumetric assessment of white matter lesions was performed on the 1.5 T scan. The percentage of voxels with a significant signal change on breath-holding and the whole brain signal change were calculated as measures of cerebrovascular reactivity. The mean percentage of voxels with a significant signal change was 25.1% (SD 6.6) and the mean percentage whole brain signal change was 1.20% (SD 0.51). Age, gender, and diastolic blood pressure were significantly associated with cerebrovascular reactivity. Cerebrovascular reactivity was lower with increasing age, lower in females compared to males and lower with lower diastolic blood pressure. ANCOVA showed that patients with microbleeds (n=18) had a significantly lower whole brain signal change than patients without microbleeds, with a mean difference of -0.36% (95% CI -0.64 to 0.07), independent of age, sex, systolic and diastolic blood pressure and non-lacunar infarcts. No significant associations were found for presence of lacunar infarcts or white matter lesion volume with whole brain signal change or percentage of voxels with a significant signal change. The results show that presence of microbleeds is associated with an impaired cerebrovascular reactivity in patients with atherosclerotic disease, whereas no significant association was found for the presence of lacunar infarcts or white matter lesions in our study.