EXPRESS: Cerebral blood flow-oxygen metabolism uncoupling at 24 hours after stroke thrombectomy
Carolyn A Lomahan, Georgios Kalarakis, Marie Luby, Staffan Holmin, Johan Lundberg, Michael V Mazya, Lawrence L Latour, Fabian Arnberg-SandorBackground
Following successful endovascular therapy (EVT) for acute ischemic stroke, tissue with abnormal perfusion may have impaired oxygen extraction and metabolism. MRI model-based oxygen extraction fraction (OEFmax) and cerebral metabolic rate of oxygen (CMRO2) were characterized in hypoperfusion and hyperemia regions 24 hours post-EVT.
Methods
Eighty-four patients were included with anterior circulation vessel occlusion, successful recanalization, and an MRI at 24 hours post-EVT. Time-to-maximum (Tmax) and cerebral blood flow (CBF) were evaluated for hypoperfusion and hyperemia. CBF, OEFmax, and CMRO2 were quantified using i) segmentation-based and ii) single slice region of interest (ROI) analyses. Normalized CBF, OEFmax, and CMRO2 were calculated by dividing the segmentation or ROI value by the contralateral value.
Results
Sixty-seven (80%) patients had abnormal perfusion; hypoperfusion in 22 (26%), hyperemia in 36 (43%), and both in 9 (11%). Compared to control, hypoperfused regions demonstrated a 62% CBF decrease, 52% CMRO2 decrease, and 68% OEFmax increase (p<0.01). Hyperemic regions demonstrated a 58% CBF increase, 26% CMRO2 increase, and 25% OEFmax decrease (p<0.01). Hyperemia had no significant correlation between normalized CBF and CMRO2 (p=0.14).
Conclusion
Hyperemia regions demonstrated cerebral blood flow-oxygen metabolism uncoupling, suggesting the underlying mechanism as loss of cerebrovascular autoregulation rather than hypermetabolic demand.