title: Cerebral vasoreactivity: a comparison of color velocity imaging quantification and stable xenon-enhanced CT.
abstract: OBJECTIVE
  Compromised cerebral vasoreactivity increases the risk of stroke. In this study, we sought to determine whether extracranial arterial blood flow volume measured on color velocity imaging quantification could be predictive of cerebral vasoreactivity after the administration of acetazolamide.
  
  
  METHODS
  Cerebral blood flow and extracranial arterial blood flow volume of 35 patients with symptomatic carotid occlusive disease were measured before and after the administration of acetazolamide on stable xenon CT and color velocity imaging quantification, respectively. The changes in unilateral extracranial arterial blood flow volume and respective hemispheric cerebral blood flow were compared. The mean difference in the percentage of change in flow volume, the 95% limit of agreement, and Cohen's kappa coefficient were calculated.
  
  
  RESULTS
  A total of 64 unilateral extracranial arterial blood flow volume changes were successfully compared with the changes in the ipsilateral hemispheric cerebral blood flow. The mean difference in percentage of change in flow volume between the two techniques was 4.7%, with the 95% limit of agreement ranging from -90.2% to 99.7%. Cohen's kappa coefficient was 0.41 (95% confidence interval, 0.13-0.68; p = 0.001).
  
  
  CONCLUSIONS
  The performance of color velocity imaging quantification for evaluating cerebral vasoreactivity is comparable to that of transcranial Doppler sonography. Because color velocity imaging quantification is not as limited as transcranial Doppler sonography, it could be an ideal complementary tool to transcranial Doppler sonography. More studies are required to define its clinical value.
authors.affiliation: Department of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, Ngan Shing St., Shatin, New Territories, Hong Kong.
authors.forename: S S Y
authors.initials: SS
authors.lastname: Ho
authors.forename: W W-M
authors.initials: WW
authors.lastname: Lam
authors.forename: S C P
authors.initials: SC
authors.lastname: Ng
authors.forename: M K
authors.initials: MK
authors.lastname: Lam
authors.forename: M T V
authors.initials: MT
authors.lastname: Chan
authors.forename: W S
authors.initials: WS
authors.lastname: Poon
authors.forename: C
authors.initials: C
authors.lastname: Metreweli
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D003116:Color; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D014057:Tomography, X-Ray Computed / Q000379:methods; D014664:Vasodilation; D014978:Xenon
chemical_list: D014978:Xenon