Longitudinal Evolution of Cerebral Metabolic Rate of Oxygen in Patients with Successfully Reperfused Ischemic Stroke

The cerebral metabolic rate of oxygen (CMRO₂) provides a direct measure of brain tissue metabolism and function, making it valuable in understanding physiologic changes in infarct tissue in patients with ischemic stroke. However, changes in cerebral metabolism and their significance in infarct tissue postreperfusion remain underexplored. In this study, we examined the longitudinal changes in CMRO₂ in infarct tissue in successfully reperfused patients with ischemic stroke.

Fifty-one patients with ischemic stroke with anterior circulation large vessel occlusion who underwent successful endovascular thrombectomy (EVT) were screened from a prospective longitudinal multicenter study. MRI scans obtained at 3 post-EVT time points generated CBF and oxygen extraction fraction maps, from which CMRO₂ maps were calculated. Mean CMRO₂ values of manually delineated infarct regions of interest and contralateral homologs were extracted, and relative CMRO₂ values (ratio of infarct and contralateral CMRO₂ values) were analyzed. The 3-month mRS scores were binarized into disabled (mRS >1) and nondisabled (mRS ≤1), and relative CMRO₂ was compared between the groups cross-sectionally and longitudinally.

Relative CMRO₂ values decreased significantly from 24 to 72 hours to 3 months (P < .001). Relative CMRO₂ was significantly higher in the nondisabled patients than in the disabled patients at all time points, except at 24-72 hours. Longitudinal analysis in both nondisabled and disabled patients revealed a significant decrease in the relative CMRO₂ values from 24 to 72 hours to 3 months (P < .001 for both). A visual-but-nonsignificant difference in the CMRO₂ trajectory was observed between the 2 groups after 3 months.

Post successful thrombectomy, relative cerebral metabolism in the infarct is elevated in the acute stage, before stabilizing across time. Patients with better functional outcomes consistently show better cerebral metabolism than patients with poor functional outcomes.