Quantitative mapping of cerebrovascular reactivity amplitude and delay with breath-hold BOLD fMRI when breath-hold task compliance is low

Motivation: Cerebrovascular reactivity (CVR) indicates cerebrovascular health and is often measured using breath-hold tasks during fMRI scanning. Measuring end-tidal CO2 (PETCO2) during the scan allows CVR amplitude to be calculated in standard units, enabling comparisons across subjects. Accurately measuring breath-hold PETCO2 is challenging, particularly in clinical populations. Goal(s): Our goal is to develop a method for modeling CVR in standard units when PETCO2 quality is low. Approach: We evaluated 2 alternative regressors (RVT and predicted PETCO2) for modeling CVR in standard units. Results: Both regressors enable robust CVR mapping in standard units in low-quality data; predicted PETCO2 may offer greater sensitivity to cerebrovascular pathology. Impact: The proposed methods model cerebrovascular reactivity in standard units, facilitating comparisons across subjects and with established healthy ranges. This work will increase the feasibility of mapping cerebrovascular function in clinical populations with variable breath-hold task compliance.