Reliable Quantification of Cerebrovascular Reactivity Despite Poorly Performed Breath-Holds

Kevin Murphy¹, Molly G. Bright¹

Cerebrovascular reactivity, the vascular response to vasodilatory stimuli, can be measured with BOLD fMRI by increasing end-tidal CO₂ using a breath-hold task. A long end-expiration breath-hold lasting 20s provides a suitably large BOLD response. However, clinical and elderly populations may find such a long breath-hold difficult and it is likely that the length of breath-hold that each participant can achieve will vary widely across these groups. This study demonstrates that by measuring end-tidal CO₂ changes during a breath-hold task, a repeatable measure of cerebrovascular reactivity can be obtained irrespective of whether the participant can perform the task fully or consistently.