title: The anatomic variations of the circle of Willis in preterm-at-term and term-born infants: an MR angiography study at 3T.
abstract: OBJECTIVE
  It has been shown that the brain of a preterm infant develops differently from that of a term infant, but little is known about the neonatal cerebrovascular anatomy. Our aims were to establish reference data for the prevalence of the anatomic variations of the neonatal circle of Willis (CoW) and to explore the effect of prematurity, MR imaging abnormality, vascular-related abnormality, laterality, and sex on these findings.
  
  
  METHODS
  We scanned 103 infants with an optimized MR angiography (MRA) protocol. Images were analyzed for different variations of the CoW, and results were compared for the following: 1) preterm-at-term and term-born infants, 2) infants with normal and abnormal MR imaging, 3) infants with and without a vascular-related abnormality, 4) boys and girls, and 5) left- and right-sided occurrence.
  
  
  RESULTS
  The most common anatomic variation was absence/hypoplasia of the posterior communicating artery. Preterm infants at term had a higher prevalence of a complete CoW and a lower prevalence of anatomic variations compared with term-born infants; this finding was significant for the anterior cerebral artery (P = .02). There was increased prevalence of variations of the major cerebral arteries in those infants with vascular-related abnormalities, statistically significant for the posterior cerebral artery (P = .004). There was no statistically significant difference between boys and girls and left/right variations.
  
  
  CONCLUSIONS
  Prematurity is associated with more complete CoWs and fewer anatomic variations. In vascular-related abnormalities, more variations involved major arterial segments, but fewer variations occurred in the communicating arteries. Overall reference values of the variations match those of the general adult population.
authors: Department of Imaging Sciences, Imperial College London, London, UK. christina.malamateniou03@imperial.ac.uk
authors: C
authors: C
authors: Malamateniou
authors: M E
authors: ME
authors: Adams
authors: L
authors: L
authors: Srinivasan
authors: J M
authors: JM
authors: Allsop
authors: S J
authors: SJ
authors: Counsell
authors: F M
authors: FM
authors: Cowan
authors: J V
authors: JV
authors: Hajnal
authors: M A
authors: MA
authors: Rutherford
mesh_terms: D002533:Cerebral Angiography / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D002941:Circle of Willis / Q000002:abnormalities* / Q000033:anatomy & histology*; D000013:Congenital Abnormalities / Q000453:epidemiology* / Q000473:pathology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D021621:Imaging, Three-Dimensional; D007231:Infant, Newborn; D007234:Infant, Premature; D018810:Magnetic Resonance Angiography / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D008297:Male; D015995:Prevalence; D012016:Reference Values