Effect of Graded O2 Challenge On Vascular & Metabolic Parameters

Feng Xu¹, Peiying Liu¹, Hanzhang Lu¹

Calibrated fMRI relies on an iso-CMRO2 challenge to obtain the calibration factor. O2 challenge has been proposed to be a potential method for the calibration experiment. However, the assumption that O2 challenge is iso-CMRO2 has not been validated. The present study will investigate whether physiologic manipulation of O2 content in the arterial blood will change brain metabolism. We used a recently developed TRUST MRI technique to monitor the subjects CMRO2 while altering the O2 concentration in the inspired air. Our data suggest that O2 content changes brain metabolism and an inverse relationship was observed between CMRO2 and arterial O2 content.