Reference values of the prevalence of anatomic variations of the CoW in a group of 65 infants (24 term-born, 41 preterm-at-term) with normal MR imaging findings
| Term (normal MRI) n = 24 | Preterm (normal MRI) n = 41 | P Value | Mean | |
|---|---|---|---|---|
| Completeness of CoW | 9 in 24 (37.5%) | 18 in 41 (44%) | .405 | 41.50% |
| AcomA absence/hypoplasia | 6 in 24 (25%) | 6 in 41 (14.6%) | .237 | 18.50% |
| PcomA absence/hypoplasia | 13 in 48 (27%) | 26 in 82 (31.7%) | .363 | 30% |
| A1 segment of ACA absence/hypoplasia | 5 in 48 (10.4%) | 1 in 82 (1.2%) | .026* | 4.60% |
| P1 segment of PCA absence/hypoplasia | 4 in 48 (8.3%) | 4 in 82 (4.8%) | .332 | 6.10% |
| Fetal-type origin of PCA | 14 in 48 (29%) | 22 in 82 (26.8%) | .463 | 27.70% |
| Transitional-configuration origin of PCA | 6 in 48 (12.5%) | 4 in 82 (4.8%) | .11 | 5.40% |
| Bilateral fetal-type origin | 8 in 14 (57.1%) | 14 in 22 (63.6%) | .482 | 61.10% |
| Bilaterally absent PcomA | 6 in 13 (46.2%) | 14 in 26 (53.8%) | .455 | 51.30% |
Note:—CoW indicates circle of Willis; MRI, MR imaging; AcomA, anterior communicating artery; PcomA, posterior communicating artery; ACA, anterior cerebral artery; PCA, posterior cerebral artery.
* Statistically significant.