title: Blood-oxygen level dependent MRI measures of cerebrovascular reactivity using a controlled respiratory challenge: reproducibility and gender differences.
abstract: OBJECTIVE
  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)).
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Physiology and Experimental Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada. andrea.kassner@utoronto.ca
authors.forename: Andrea
authors.initials: A
authors.lastname: Kassner
authors.forename: Jeff D
authors.initials: JD
authors.lastname: Winter
authors.forename: Julien
authors.initials: J
authors.lastname: Poublanc
authors.forename: David J
authors.initials: DJ
authors.lastname: Mikulis
authors.forename: Adrian P
authors.initials: AP
authors.lastname: Crawley
mesh_terms: D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology*; D001921:Brain / Q000098:blood supply / Q000187:drug effects / Q000502:physiology*; D002245:Carbon Dioxide / Q000008:administration & dosage*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D011659:Pulmonary Gas Exchange / Q000187:drug effects / Q000502:physiology*; D012737:Sex Factors; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen