title: Reproducibility of cerebrovascular reactivity measures in children using BOLD MRI.
abstract: OBJECTIVE
  To evaluate the reproducibility of cerebrovascular reactivity (CVR) measurements acquired in children using magnetic resonance imaging (MRI) in combination with a computer-controlled carbon dioxide (CO2 ) stimulus.
  
  
  METHODS
  Ten healthy children (age 16.1 ± 1.6 years) underwent CVR imaging on a 3T scanner using a blood-oxygen level-dependent (BOLD) MRI sequence. Targeted hypercapnia was induced during imaging with a CO2 gas challenge delivered using a specialized gas sequencer (RespirAct). A total of four BOLD scans were performed over 2 separate days to test within-day and between-day consistency of the data. CVR values were computed by correlating the relative change in BOLD signal in response to the CO2 stimulus delivered to the each subject.
  
  
  RESULTS
  Intraclass correlation coefficients (ICCs) of within-day values show highly reproducible measures in both the gray matter (ICC = 0.857, P < 0.001) and white matter (ICC = 0.895, P < 0.001). Relatively lower between-day reproducibility was observed in both the gray matter (ICC = 0.776, P = 0.001) and white matter (ICC = 0.719, P = 0.004).
  
  
  CONCLUSIONS
  Using a computer-controlled CO2 stimulus, we have demonstrated the reliability of BOLD-CVR measurements in pediatric subjects. Within-day and between-day metrics of reproducibility were comparable to adult data.
authors.affiliation: Department of Physiology and Experimental Medicine, the Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Jackie
authors.initials: J
authors.lastname: Leung
authors.affiliation: Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Junseok A
authors.initials: JA
authors.lastname: Kim
authors.affiliation: Department of Physiology and Experimental Medicine, the Hospital for Sick Children, Toronto, Ontario, Canada.|Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Andrea
authors.initials: A
authors.lastname: Kassner
mesh_terms: D000293:Adolescent; D001921:Brain / Q000000981:diagnostic imaging; D001931:Brain Mapping / Q000379:methods; D002245:Carbon Dioxide / Q000737:chemistry*; D002560:Cerebrovascular Circulation; D003201:Computers; D005260:Female; D006706:Homeostasis; D006801:Humans; D006935:Hypercapnia / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008297:Male; D009038:Motion; D015203:Reproducibility of Results
chemical_list: D002245:Carbon Dioxide
keywords: BOLD MRI; cerebrovascular reactivity; pediatric; reproducibility