MR Based Quantification of Global Cerebral Metabolic Rate of Oxygen Consumption During Hypercapnia

Varsha Jain¹, Michael Langham¹, Thomas T. Floyd², Jeremy F. Magland¹, Felix W. Wehrli¹

Hypercapnia is a common occurrence in pathophysiologic conditions and is also used as a diagnostic tool to measure cerebral vascular reactivity to assess the integrity of cerebral circulation which can be altered in pathophysiological states. While the vascular effects of hypercapnia on cerebral blood flow have been well documented, there is no general consensus on its metabolic effects. Additionally from a neuroscience research perspective, assumption of constant cerebral metabolic rate of oxygen consumption (CMRO2) during hypercapnia is used for calibrating blood oxygen-level dependent (BOLD) response in functional magnetic resonance imaging, yet verification is pending. Hence, we propose a robust and reliable method for quantifying CMRO2 during hypercapnia by simultaneously measuring total cerebral blood flow (tCBF) and venous oxygen saturation (SvO2) in the major cerebral supply and drainage vessels during hypercapnia with a temporal resolution of ~30s.