Hyperoxic versus Hypercapnic BOLD Calibration Under Precise End-Tidal Control to Improve the Estimation of Oxygen Consumption

Clarisse Ildiko Mark¹, Gilbert Bruce Pike¹

Estimates of changes in cerebral metabolic rate of oxygen (ΔCMRO₂) and coupling relationship (n) to blood flow (ΔCBF) under neuronal activation, crucial in interpreting BOLD results, are highly sensitive to variability in individual subjects calibration (M)-values and brain regions. We thereby sought to acquire precise calibration data under robust control of hypercapnic (HC) and hyperoxic (HO) levels, together with visual stimulation and motor tasks in the same set of subjects. Based on low-variability M-values, our findings demonstrate significantly decreased variability in CMRO₂- and n-estimates under HC, and even better under HO.