Mapping Grey Matter Cerebrovascular Reactivity and Oxygen Consumption Using Resting-State BOLD-ASL Functional MRI

BOLD and ASL CBF fMRI can measure cerebrovascular reactivity (CVR) following a vasodilatory stimulus such as hypercapnia. BOLD and ASL CVR measurements allow us to extract the maximum BOLD signal modulation from which, through biophysical modelling, OEF and CMRO2 can be inferred. We measured these physiological variables in grey matter by assessing the resting-state coupling between fMRI and end-tidal CO2 (reflecting arterial CO2) recordings. In-vivo evaluation of two, sequentially acquired, 14-min recordings at rest demonstrated the method’s good repeatability. This simplified calibrated fMRI approach does not require an exogenous hypercapnic stimulus and thus holds promise for future applications.