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Abstract #0766

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

Clarisse Ildiko Mark1, Gilbert Bruce Pike1

1McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada

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.