title: MR assessment of cerebral vascular response: a comparison of two methods.
abstract: OBJECTIVE
  To compare the results and reproducibility of two MR-based methods of measuring the cerebrovascular response (CVR).
  
  
  METHODS
  In eight volunteers, CVR was assessed with two MR-based methods upon a challenge with acetazolamide. CVR was assessed by measuring changes in total cerebral blood flow (TCBF) using phase contrast (PC) MRI, and by measuring perfusion MRI. To assess reproducibility the measurements were repeated after 1 week.
  
  
  RESULTS
  The average CVR with the PC-MRI method was 46% (SD = 16%), and for perfusion MR the measured CVR was 44% (SD = 16%). The coefficient of variation (COV) for PC-MRI was 28%, while perfusion MR had a COV of 26%. The limits of agreement between the two methods were -49% and 45%, demonstrating a lack of agreement between the two methods in terms of CVR estimation.
  
  
  CONCLUSIONS
  CVR estimates based on PC-MRI and perfusion MRI showed reproducibility but a lack of agreement in healthy volunteers. This lack of agreement can be attributed to the different aspects of the CVR reflected by these methods: TCBF reflects changes in CBF, whereas our perfusion MRI method reflects cerebral blood volume (CBV).
authors.affiliation: Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands. a.spilt@lumc.nl
authors.forename: Aart
authors.initials: A
authors.lastname: Spilt
authors.forename: Rivka
authors.initials: R
authors.lastname: Van den Boom
authors.forename: Adriaan M
authors.initials: AM
authors.lastname: Kamper
authors.forename: Gerard J
authors.initials: GJ
authors.lastname: Blauw
authors.forename: Edward L E M
authors.initials: EL
authors.lastname: Bollen
authors.forename: Mark A
authors.initials: MA
authors.lastname: van Buchem
mesh_terms: D000086:Acetazolamide / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D001810:Blood Volume; D002560:Cerebrovascular Circulation / Q000187:drug effects; D003287:Contrast Media; D005682:Gadolinium; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D015203:Reproducibility of Results; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D003287:Contrast Media; D014665:Vasodilator Agents; D005682:Gadolinium; D000086:Acetazolamide