Comparison of Breath Holding Techniques for the Calibration of FMRI Measurements of Oxygen Metabolism

Peter Roberts¹, Peter Jezzard¹, Daniel Bulte¹

Changes in the cerebral metabolic rate of oxygen consumption (CMRO2) during functional brain activity can be estimated from fMRI measurements of cerebral blood flow (CBF) and the blood oxygenation level dependent (BOLD) signal. A common method of calibrating the calculation uses breath holds to induce hypercapnia, which causes changes in cerebral blood oxygenation and flow. It has been debated whether it is better, either due to differences in physiology or magnetic field shim quality, to hold the breath after inspiration or expiration. The present study compared the two techniques by acquiring interleaved BOLD and CBF fMRI images from six subjects.