title: Interrelation between the degree of carotid stenosis, collateral circulation and cerebral perfusion.
abstract: BACKGROUND
  In patients with carotid artery stenosis, ipsilateral hemodynamic compromise is associated with an increased risk of stroke. It is unclear which factors determine cerebral perfusion. We studied the effect of both the degree of the stenosis and the collateral circulation via the circle of Willis (CoW) on cerebral perfusion in patients with symptomatic carotid artery stenosis.
  
  
  METHODS
  In 88 patients with unilateral symptomatic carotid artery stenosis of > or =50%, CT perfusion was used to measure the relative cerebral blood volume (rCBV), the difference in mean transit time (DeltaMTT) and the relative cerebral blood flow (rCBF). CT angiography was used to measure the degree of carotid stenosis and to assess the configuration of the CoW. Differences in mean rCBF, rCBV and DeltaMTT between patients with a carotid stenosis of < or =69, 70-79, 80-89 and 90-99%, and between patients with a complete and those with an incomplete CoW were determined by analysis of covariance.
  
  
  RESULTS
  The ipsilateral rCBF showed a gradual decrease with increasing severity of carotid stenosis (1.09 +/- 0.06, 0.93 +/- 0.06, 0.90 +/- 0.04 and 0.83 +/- 0.04 ml/100 g/min, respectively; p = 0.005), and the DeltaMTT showed a gradual increase (-0.02 +/- 0.33, 0.16 +/- 0.34, 1.08 +/- 0.22 and 1.47 +/- 0.20 s, respectively; p < 0.001). The rCBV was not related to the severity of stenosis. No relation was found between the configuration of the CoW and the cerebral perfusion parameters.
  
  
  CONCLUSIONS
  Cerebral perfusion is inversely related to the degree of stenosis in patients with symptomatic carotid artery stenosis. A relation between the configuration of the CoW and cerebral perfusion was not detected, suggesting that other collateral pathways play an important role.
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands. L.Jongen@umcutrecht.nl
authors.forename: L M
authors.initials: LM
authors.lastname: Jongen
authors.forename: H B
authors.initials: HB
authors.lastname: van der Worp
authors.forename: A
authors.initials: A
authors.lastname: Waaijer
authors.forename: Y
authors.initials: Y
authors.lastname: van der Graaf
authors.forename: W P T M
authors.initials: WP
authors.lastname: Mali
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016893:Carotid Stenosis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002533:Cerebral Angiography / Q000379:methods*; D002941:Circle of Willis / Q000502:physiology; D003097:Collateral Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging / Q000379:methods*; D012039:Regional Blood Flow / Q000502:physiology; D012189:Retrospective Studies; D012720:Severity of Illness Index