title: Anatomy of the circle of Willis and blood flow in the brain-feeding vasculature in prematurely born infants.
abstract: BACKGROUND
  Previous studies have shown a disrupted development of cerebral blood vessels at term-equivalent age in prematurely born infants.
  
  
  OBJECTIVE
  To assess the anatomy of the circle of Willis in preterm neonates (gestational age 25-31 weeks) at term-equivalent age and to evaluate the relation between anatomic variations and blood flow through the internal carotid arteries (ICAs) and basilar artery (BA).
  
  
  METHODS
  In 72 preterm neonates, flow measurements (ml/min) were obtained with 2-D phase-contrast magnetic resonance angiography (MRA) at term-equivalent age. Time-of-flight MRA was used to assess the circle of Willis for a dominant A1 segment of the anterior cerebral artery or a fetal-type posterior cerebral artery. Differences in flow were assessed with ANOVA.
  
  
  RESULTS
  In our cohort, 53/72 (74%) neonates showed a variant type of the circle of Willis. The flow in the ICA at the side of a dominant A1 segment (43.3 ml/min) was significantly increased compared to the flow in the contralateral ICA (33.0 ml/min; p = 0.009) and tended to be higher than in the ICA in children with a normal anterior anatomy (38.4 ml/min; p = 0.1). The flow in the BA was highest in neonates with a normal configuration of the posterior part of the circle of Willis (32.6 ml/min) compared to children with a unilateral (25.3 ml/min; p = 0.002) or bilateral fetal-type posterior cerebral artery (18.6 ml/min; p < 0.001).
  
  
  CONCLUSIONS
  Preterm neonates show a high prevalence of variant types of the circle of Willis at term-equivalent age. A relation could be demonstrated between variations in the circle of Willis and the flow in the ICA and BA.
authors.affiliation: Department of Neonatology, Wilhelmina Children's Hospital/University Medical Centre, NL-3508 AB Utrecht, The Netherlands. B.vanKooij-4 @ umcutrecht.nl
authors.forename: B J M
authors.initials: BJ
authors.lastname: van Kooij
authors.forename: J
authors.initials: J
authors.lastname: Hendrikse
authors.forename: M J N L
authors.initials: MJ
authors.lastname: Benders
authors.forename: L S
authors.initials: LS
authors.lastname: de Vries
authors.forename: F
authors.initials: F
authors.lastname: Groenendaal
mesh_terms: D000328:Adult; D001488:Basilar Artery / Q000033:anatomy & histology / Q000502:physiology; D001921:Brain / Q000033:anatomy & histology / Q000098:blood supply* / Q000000981:diagnostic imaging; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000502:physiology; D002941:Circle of Willis / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D015331:Cohort Studies; D004622:Embryo, Mammalian; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology; D018810:Magnetic Resonance Angiography / Q000379:methods; D008954:Models, Biological; D047928:Premature Birth / Q000503:physiopathology; D011859:Radiography; D012039:Regional Blood Flow / Q000502:physiology*