Blood‐oxygen level dependent MRI measures of cerebrovascular reactivity using a controlled respiratory challenge: Reproducibility and gender differences

PURPOSE: To evaluate the reproducibility and gender differences in cerebrovascular reactivity (CVR) measurements obtained using the blood-oxygen level dependent (BOLD) response to controlled changes in end-tidal partial pressure of carbon dioxide (PETCO(2)). MATERIALS AND METHODS: We obtained ethical approval to image 19 healthy volunteers (10 men, 9 women) on a 1.5 Tesla (T) MRI scanner twice on two separate days using identical procedures. CVR images were generated by collecting BOLD MRI data during controlled changes in PETCO(2) induced by a sequential gas delivery system. RESULTS: Using the intraclass correlation coefficient (ICC), we demonstrated excellent within-day CVR measures in gray matter (GM) (ICC = 0.92) and white matter (WM) (ICC = 0.88) regions, excellent between-day reproducibility in GM (ICC = 0.81), and good between-day reproducibility in the WM (ICC = 0.66). CVR values between men and women were significantly different in the GM and WM. Men exhibited a 22 +/- 2% greater CVR in GM and a 17 +/- 2% greater CVR in WM compared with females. CONCLUSION: Our results demonstrate the reliability of BOLD MRI CVR measurements obtained using a controlled cerebrovascular challenge. Using this technique, we also revealed significantly increased BOLD response to CO(2) in males compared with females.