Anatomical variations of the circle of Willis in children.

<bold>Background: </bold>The morphology of the circle of Willis in adults has been thoroughly discussed in scientific literature. However, the morphology of the circle of Willis in pediatric patients is under-researched.<bold>Objectives: </bold>We aimed to establish reference data for the morphology and variations of the circle of Willis in a population consisting of all pediatric age subgroups and to evaluate the possible temporal evolution of the circle of Willis in pediatric patients along with the variations between pediatric and adult populations.<bold>Materials and Methods: </bold>Our patient cohort included 263 pediatric patients ages 1-215 months. A total of 273 magnetic resonance (MR) angiography images were retrospectively analyzed for all circle of Willis vessels to compare the incidence of complete cases and variation frequency based on gender and age group.<bold>Result: </bold>In our study of 273 MR angiograms from all age ranges in the pediatric population, we found a 56.1% circle of Willis completion rate. Overall completion rates were statistically significantly higher in the toddler and preschool age groups. The lowest completion rate was in the newborn-infant group (40%).<bold>Conclusion: </bold>Circle of Willis completion rates and variations in pediatric populations are similar to those in adult populations; completion rates rise in toddler and preschooler age groups and decline as children grow into the school-age and adolescent period. [ABSTRACT FROM AUTHOR]