Anatomical variants of circle of Willis

Aleksandra Milenković; Slađana Petrović; Simon Nikolić; Branislava Radović; Aleksandra Ilić; Miloš Gašić; Bojan Tomić

doi:10.5937/pramed2004007m

Abstract

Introduction: The circle of Willis is the major source of collateral blood flow between the carotid and vertebrobasilar system. Its potential depends on the presence and size of arteries that vary greatly among normal individuals and therefore their adequate observation by a radiologist is necessary. Aim: Determine the type of the circle of Willis and their frequency. Determine the type, frequency and localization of anatomical variants of arteries, as well as their average diameter. Compare these variables according to the age and gender of the examinees. Material and methods: A retrospective study was performed at the Center for Radiology of the Clinical Center Nis during 2017. All subjects underwent CT or MR angiography according to a standard endocranial protocol. The anterior and posterior parts of the circle were specially observed, with an emphasis on the presence or absence of anatomical variants of the arteries, with the measurement of their diameter. The obtained data were classified into variants of the front or rear part of the ring as well as the type of ring according to integrity. The frequency of these variables and their comparison by sex and age were measured. Results: The research included 92 examinees. According to the configuration of the Willis arterial ring, the adult type was the most often represented (71.7%). The most common type in terms of integrity was partially complete. The most common anatomical variants obtained in our work was aplasia of AcoA (27.2%) and aplasia of one or both PCoA (21%). PcoA hypoplasia was occured in women with a frequency of 13.5% while in men it was not present. Conclusion: Adequate understanding of the morphology of the circle of Willis by radiological methods is a good guide for neurosurgical and radiological intervention procedures. In this way, potentially significant neurological complications and the risk of morbidity and mortality could be reduced.

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Anatomical variants of circle of Willis

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