Cerebral Blood Flow And Metabolism Associated With Cerebral Microbleeds In Patients With Non-Cardioembolic Stroke Without Major Cerebral Arterial Stenosis

Background and Purpose: Cerebral microbleeds (CMBs) are associated with not only higher age but also extensive white matter lesions (WMLs), indicating that CMBs could be a reflection of microangiopathy. CMBs have not yet been examined in association with cerebral blood flow (CBF) and metabolism. The purpose of this study was to clarify the relationships of CMBs with WMLs volume, and CBF and metabolism in patients with ischemic stroke. Methods: We enrolled 19 patients who had past history of non-cardioembolic stroke without severe stenosis (>50%) in major cerebral arteries (69±7 years, 9 women). We measured WMLs volume and counted the number of CMBs on a 1.5-T magnetic resonance imaging (MRI) scanner. CBF, cerebral blood volume, oxygen extraction fraction and cerebral metabolic rate of oxygen were measured with 15 O-labeled gas positron emission tomography (PET). We set 36 regions of interest (ROIs) in the cortex-subcortex regions, basal ganglia and centra semiovale in each patient on MRI. MRI was superimposed on PET images and 4 parameters of each ROI were calculated. Results: CMBs existed in 14 out of 19 patients (median 5; range 0-39). Patients were divided into 2 groups according to the number of CMBs; less than 5 as the group I (n=9) and 5 or more as the group II (n=10). WMLs volume of the group II was larger than that of the group I (median 38.4 with range of 25.1-91.5 vs. 10.0 with 4.2-73.4 ml, p=0.020). In the centra semiovale, CBF of the group II was significantly lower than that of the group I (12.5±2.5 vs. 15.7±3.5 ml/100g/min, p=0.031). In the other regions, there were no significant differences in all 4 parameters of PET between the 2 groups. Conclusions: We showed that the increases in the number of CMBs could indicate cerebral ischemia in the deep white matter of patients with non-cardioembolic stroke without major cerebral arterial stenosis.