Effect of Patient Body Mass, Age, and Renal Function on the Assessment of Cerebrovascular Reactivity During the Acetazolamide Challenge

ABSTRACT Background Cerebrovascular reactivity (CVR) is a blood flow index which reflects locoregional vascular health in the brain. CVR is measured using MRI with an acetazolamide (AZM) challenge. While 1000 mg of AZM is often used, there is no clear consensus on dosing. We postulate the physiologic variables—age, creatinine, and weight—may impact variation in CVR dynamics, leading to poor study reliability in different patient groups. The present study reviewed patients who underwent AZM challenge MRI examinations at our institution from 2014 to 2022. Methods Changes in CVR were evaluated at 5 and 10 min post‐AZM challenge as function of weight, BMI, age, and creatinine. Univariable data was analyzed using Pearson correlation coefficient. Results Forty‐nine patients were included in this retrospective review. Forty‐seven percent of patients identified as female, with a mean age of 55 ± 13 years, a mean BMI of 29 ± 6 kg/m 2 , and mean creatinine clearance of 0.96 ± 0.32 mg/dL. BMI was found to be significantly negatively associated with AZM response at 5 min ( r = −0.63, p = 0.002) and 10 min ( r = −0.44, p = 0.045) post‐AZM challenge. However, the present study did not demonstrate changes to CVR by creatinine or age. Conclusions CVR is underestimated with increasing body mass, possibly explained by undersaturation of carbonic anhydrase with current standardized dosages. Ubiquitous weight‐based dosing would be a superior and more reproducible predictor for CVR than standardized regimens, particularly at BMI extremes where CVR variability is significant.