title: Intracranial hemodynamics is altered by carotid artery disease and after endarterectomy: a dynamic magnetic resonance angiography study.
abstract: OBJECTIVE
  Carotid endarterectomy (CEA) has become a routine procedure to treat symptomatic carotid artery disease and reduce the risk of recurrent cerebral ischemic events. The purpose of this study was to use an arterial spin labeling dynamic magnetic resonance angiography technique to characterize intracranial hemodynamics before and after CEA.
  
  
  METHODS
  Thirty-seven carotid artery disease patients participated in this study, of whom 24 underwent magnetic resonance imaging before and after CEA. Seventeen control subjects spanning 5 decades underwent magnetic resonance imaging to assess age-related changes. Hemodynamic metrics (that is, relative time to peak and amplitude) were calculated with a γ-variate model. Linear regression was used to relate carotid artery disease burden to downstream hemodynamics in the circle of Willis.
  
  
  RESULTS
  Relative time to peak increased with age in controls (P<0.020). For patients, relative time to peak was positively correlated with percent stenosis (P<0.050), independent of age. At 1 day after CEA, the middle cerebral artery ipsilateral to the CEA showed significant dynamic magnetic resonance angiography changes: relative time to peak decreased (P<0.017) and the flow amplitude increased (P<0.009). No pre- versus post-CEA changes were significant in the contralateral middle cerebral artery or posterior segments.
  
  
  CONCLUSIONS
  This noninvasive, arterial spin labeling-based method produced time-resolved images that were used to characterize intracranial arterial flow associated with aging, extracranial carotid artery disease, and CEA. Results demonstrate that the technique has the sensitivity to detect hemodynamic changes after CEA.
authors.affiliation: Department of Clinical Neurology, FMRIB Centre, Oxfordshire, England. bmac@sri.utoronto.ca
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: MacIntosh
authors.forename: Ediri
authors.initials: E
authors.lastname: Sideso
authors.forename: Manus J
authors.initials: MJ
authors.lastname: Donahue
authors.forename: Michael A
authors.initials: MA
authors.lastname: Chappell
authors.forename: Matthias
authors.initials: M
authors.lastname: Günther
authors.forename: Ashok
authors.initials: A
authors.lastname: Handa
authors.forename: James
authors.initials: J
authors.lastname: Kennedy
authors.forename: Peter
authors.initials: P
authors.lastname: Jezzard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016893:Carotid Stenosis / Q000150:complications* / Q000503:physiopathology / Q000601:surgery; D002536:Cerebral Arteries / Q000473:pathology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D016894:Endarterectomy, Carotid / Q000009:adverse effects*; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods; D008297:Male; D008875:Middle Aged