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Abstract #1138

Hyperoxic (HO) Versus Hypercapnic (HC) BOLD Calibration Under Precise Control of End-Tidal Carbon Dioxide and Oxygen

Clarisse Ildiko Mark1, M. Slessarev2, S. Ito3, J. Han2, J. A. Fisher2, G. B. Pike1

1McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada; 2Department of Anaesthesiology, University Health Network, Univeristy of Toronto,, Toronto, Ontario, Canada; 3Department of Anaesthesiology and Medical Crisis Management, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan

Manual HC calibration depends on intrinsically low signal-to-noise perfusion imaging and individual vascular architecture, with resulting calibration (M)-values prone to large intra- and inter-subject variations that may bias oxygen metabolism studies. We thereby sough to investigate HO as a calibration alternative under rigorous control of end-tidal partial pressures of CO2 (PetCO2) and O2 (PetO2). Our findings suggest the viability of precisely controlling HO stimulation to provide more precise per-subject and per-brain-region M-estimates, based on high SNR PaO2 measurements and the removal of the confound of vascular variation in population observed under HC-calibration.