Normalisation of BOLD FMRI Data Between Different Baseline Conditions Using Hyperoxia

Daniel Bulte¹, Molly Bright^1,2, Peter Jezzard¹

The fact that BOLD FMRI is highly sensitive to resting blood flow levels is a significant limitation in the clinical application of the technique. As many commonly ingested substances can cause significant changes in CBF, correcting for this confound would be a distinct advantage in comparing between subjects, sessions or pharmacological conditions. In this study subjects were imaged during visual stimulation pre and post- caffeine consumption. Short epochs of hyperoxia were used to normalise between these 2 conditions. Despite changes in BOLD response on the order of 10-40%, the normalisation effectively reduced the baseline vascular confounds.