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Morphologic variants of the Cerebral Arterial Circle on computed tomographic angiography (CTA): a large retrospective study

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Abstract

Purpose

To confirm and illustrate the great variability of morphology of the Cerebral Arterial Circle (CAC)—also commonly called “Circle of Willis”—in current clinical Computed Tomography Angiography (CTA) practice.

Methods

Computed Tomographic Angiographic 3D Volume Rendering reconstructions of the CAC performed in a series of 511 patients were retrospectively reviewed and classified following their anatomic configuration.

Results

An amount of 27 CAC configurations were listed. Complete and “nearly complete” (1 missing segment) CACs were found in 115 (22.58%) and 157 (28.6%) patients. The posterior arch was much more frequently incomplete (374 patients = 73.18%) than the anterior arch (96 patients = 18.4%). The main cause was a high prevalence of missing posterior communicating arteries (PCoAs). The left or right PCoA were unilaterally lacking in 156 patients (30.53%) and both PCoAs were lacking in 179 patients (35.02%). Cases with 2 and 3 missing segments were observed in 184 (36%) and 44 patients (8.6%). Precarious situations were also identified including 7 cases (1.4%) of complete isolation of the middle cerebral artery (MCA), 11 cases (2.15%) of absence of interhemispheric supply, 205 cases (40.1%) of full separation of the carotid and vertebra-basilar (VB) territories and 44 cases (8.6%) of full separation of the three main arterial axes (both ICAs and VB). The prevalence of Fetal Posterior Cerebral Arteries (FPCA) variants was also reported. A “Full” FPCA was found unilaterally in 48 (9.4%) and bilaterally in 13 (2.54%) of patients. Apart from agenesis and hypoplasia reported in our study, various other variations of the anterior complex of the CAC (ACoA and A2 segments of the ACA) were also noted.

Conclusion

CTA with 3D Volume Rendering may powerfully assess the numerous variations of the CAC. This assessment is of prime importance for the evaluation of patients presenting with risk factors or in whom neurosurgery, cardiac surgery, interventional radiology or carotid endarterectomy (CEA) are being considered.

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Abbreviations

CAC:

Cerebral Arterial Circle

CTA:

Computed Tomographic Angiography

ICA:

Internal Carotid Artery

ACA:

Anterior Cerebral Artery

MCA:

Middle Cerebral Artery

PCA:

Posterior Cerebral Artery

ACoA:

Anterior Communicating Artery

PCoA:

Posterior Communicating Artery

VBT:

Vertebro Basilar Trunk

MRI:

Magnetic Resonance Imaging

MRA:

Magnetic Resonance Angiography

CDU:

Colour Doppler Ultrasound

3DVR:

3D Volume Rendering

FPCA:

Fetal Posterior Communicating Artery

CEA:

Carotid Endarteriectomy

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The authors did not receive support from any organization for the submitted work.

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  1. Departments of Diagnostic Radiology, Clinique St Luc, 5004, Bouge, Namur, Belgium

    Bruno Coulier

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  1. Bruno Coulier
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Bruno Coulier is the sole author and corresponding author of the manuscript. Bruno Coulier was the sole contributor for protocol/project development. Data collection or management. Data analysis. Manuscript writing/editing.

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Correspondence to Bruno Coulier.

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The author declare that he has no conflicts of interest concerning this article.

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The retrospective study was performed with approval of the institutional ethical board (but with the waiver of patient consent given the retrospective nature of the study) the author certifies that all data and figures have been anonymised.

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Coulier, B. Morphologic variants of the Cerebral Arterial Circle on computed tomographic angiography (CTA): a large retrospective study. Surg Radiol Anat 43, 417–426 (2021). https://doi.org/10.1007/s00276-020-02661-x

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