Cerebrovascular reactivity (CVR) mapping can be achieved by BOLD MRI during hypercapnia challenges, such as a breath-hold (BH) task. It has wide applications for the assessment of various neurological deficits and neurovascular uncoupling. The BH MRI is typically analyzed by modeling with a hemodynamic or respiratory response function and account for latencies in signal time courses. Accurate modeling requires physiological monitoring and/or consistent patient performance during the scan. Because the BOLD signal response to the BH is a global effect, this study proposes to utilize the individual’s whole-brain signal average as a regressor for the analysis of BH MRI.