The role of the circle of Willis in internal carotid artery stenosis and anatomical variations: a computational study based on a patient-specific three-dimensional model.

Joon Hock Yeo,Guangyu Zhu,Jian Yang,Qi Yuan

doi:10.1186/s12938-015-0105-6

Abstract

BackgroundThe aim of this study is to provide better insights into the cerebral perfusion patterns and collateral mechanism of the circle of Willis (CoW) under anatomical and pathological variations.MethodsIn the current study, a patient-specific three-dimensional computational model of the CoW was reconstructed based on the computed tomography (CT) images. The Carreau model was applied to simulate the non-Newtonian property of blood. Flow distributions in five common anatomical variations coexisting with different degrees of stenosis in the right internal carotid artery (RICA) were investigated to obtain detailed flow information.ResultsWith the development of stenosis in unilateral internal carotid artery (ICA), the cerebral blood supply decreased when the degree of stenosis increased. The blood supply of the ipsilateral middle cerebral artery (MCA) was most affected by the stenosis of ICA. The anterior communicating artery (ACoA) and ipsilateral posterior communicating artery (PCoA) functioned as the important collateral circulation channels when unilateral stenosis occurred. The blood flow of the anterior circulation and the total cerebral blood flow (CBF) reached to the minimum in the configuration of the contralateral proximal anterior cerebral artery (A1) absence coexisting with unilateral ICA stenosis.ConclusionsCommunicating arteries provided important collateral channels in the complete CoW when stenosis in unilateral ICA occurred. The cross-flow in the ACoA is a sensitive indicator of the morphological change of the ICA. The collateral function of the PCoA on the affected side will not be fully activated until a severe stenosis occurred in unilateral ICA. The absence of unilateral A1 coexisting with the stenosis in the contralateral ICA could be the most dangerous configuration in terms of the total cerebral blood supply. The findings of this study would enhance the understanding of the collateral mechanism of the CoW under different anatomical variations.

Highlights

The aim of this study is to provide better insights into the cerebral perfusion patterns and collateral mechanism of the circle of Willis (CoW) under anatomical and pathological variations
We investigated the cerebral blood perfusion in the CoW of different configurations coexisting with various severities of stenosis in unilateral internal carotid arteries (ICA)
The simulations showed in the complete CoW, anterior communicating artery (ACoA) and ipsilateral posterior communicating arteries (PCoA) functioned as the important collateral channels when stenosis in unilateral ICA occurred

Summary

Introduction

The aim of this study is to provide better insights into the cerebral perfusion patterns and collateral mechanism of the circle of Willis (CoW) under anatomical and pathological variations. The circle of Willis (CoW), a ring-like arterial structure located at the base of the brain, is a cerebral blood supply path [2] as well as a primary cerebral collateral flow channel. It consists of a single anterior communicating artery (ACoA), paired anterior cerebral arteries (ACA), middle cerebral arteries (MCA), internal carotid arteries (ICA), posterior communicating arteries (PCoA), posterior cerebral arteries (PCA), single basilar artery (BA) and vertebral arteries (VA). Typical anatomical variations include the absence of ACoA, unilateral or bilateral PCoA, fetal type arteries, and fused vessels [6] Such variations undermine the compensational capability of the cerebral arteries and subsequently result in undesirable clinical consequences, including transient ischemic attack (TIA) and ischemic stroke. A detailed knowledge of the cerebral blood distribution and collateral flow patterns of the CoW under anatomical and pathological variations is important for understanding the collateral mechanism of the CoW, and valuable for early diagnosis and pre-operation planning of the cerebral vascular diseases

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