Michael Germuska1, Daniel P. Bulte1
University of Oxford, Oxford, Oxon, United Kingdom
This study consisted of a direct comparison between cerebrovascular reactivity (CVR) to 5% CO2 in air and 5% CO2 in oxygen (carbogen). We found that CVR as measured by BOLD and ASL response are correlated for CO2 in air but not under a carbogen stimulus. In addition flow CVR as measured by ASL is strongly affected by inspired oxygen fraction and is not consistent between these two stimuli. We conclude that BOLD imaging should not be used in conjunction with a carbogen stimulus to measure CVR, and that flow CVR values acquired with carbogen and CO2/air are not directly comparable.