Uncertainties in baseline cerebral oxidative metabolism mapping by gas-free and dual-calibrated fMRI: a simulation-based comparison

Calibrated BOLD fMRI is becoming a method of choice in assessing baseline cerebral oxidative metabolism (CMRO2), with gas-free calibrated fMRI being an non-invasive alternative to the more established gas-calibrated fMRI methods. However, the relative repeatabilities of these two approaches are unknown, each depending on a unique set of input measurements. This study uses analytical simulations to investigate the sensitivity of baseline OEF and CMRO2 estimates to the measured inputs of each method. Our results suggest that gas-free calibrated fMRI is substantially less sensitive to input variations than gas-calibrated fMRI, demonstrating the potential for simulation-informed methodological selection.