Circle of Willis artery diameters on MR angiography: an Australian reference database
E N El-Barhoun1, S R Gledhill, A G Pitman
1Department of Radiology, The Queen Elizabeth Hospital, Adelaide, South Australia, Australia. esber.el-barhoun@nwahs.sa.gov.au
Insights
This study establishes reference ranges for Circle of Willis (COW) arteries in an Australian population undergoing brain MRI/MRA. Vessel size was consistent across demographics and COW variants, with age impacting basilar artery diameter.
Area of Science:
- Neuroimaging
- Vascular Anatomy
- Radiology
Background:
- The Circle of Willis (COW) is crucial for brain blood supply.
- Establishing population-specific reference ranges for COW arteries is important for diagnosing vascular conditions.
- Previous studies have not comprehensively defined COW artery measurements for an Australian tertiary referral hospital population.
Purpose of the Study:
- To establish reference ranges for major Circle of Willis (COW) arteries in an Australian patient cohort undergoing brain MRI and MRA.
- To determine the prevalence of COW variants within this population.
- To investigate potential associations between COW variants and disease status, demographics, or aneurysm location.
Main Methods:
- Retrospective analysis of diagnostic brain MRI and MRA studies from 2006.
- One radiologist measured major COW artery diameters at defined locations.
- Interobserver variability assessed on a subset; statistical analyses included t-tests and logistic regression.
Main Results:
- Reference ranges were established for major COW arteries in 171 Australian patients.
- Vessel calibre was comparable across MRI disease status, gender, and COW variants (P > 0.05).
- Basilar artery diameter showed a significant association with age; other diameters did not. Age-related increase in discontinuous COW variants noted, potentially linked to atherosclerosis.
Conclusions:
- The established COW reference range is applicable to Australian tertiary referral hospital populations.
- Methodology is straightforward and robust to interobserver variability.
- COW variants increase with age, possibly due to atherosclerosis, but show no association with gender, aneurysm location, or MRI disease status.
Abstract:
The aim was to establish a reference range of measurements for all major Circle of Willis (COW) arteries for an Australian population of patients presenting for brain magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) that is typical of a tertiary referral hospital; and to report the prevalence and disease associations of COW variants in our patient population. All technically diagnostic MRI and MRA studies performed at our magnetic resonance (MR) centre in the calendar year 2006 were re-read by one reader who classified the COW anatomical layout and measured diameters of all the major vessels at defined locations. A subset of 30 was independently re-read by another reader and the interobserver measurement variability analyzed. Graphical analysis, with 95% confidence intervals (95CI), summary statistics reporting, t-testing for unpaired and for paired means, Hauck-Anderson (H-A) clinical equivalence testing and logistic regression analysis for categorical variables was performed as relevant. One hundred and seventy-one studies (of 187 eligible) formed the analysis population. All of our patients had vessels of comparable calibre regardless of MRI disease status, gender or COW variant (P > 0.05). Basilar artery (BA) diameter showed significant association with age, but other vessel diameters did not. The reference range is widely applicable, methodology straightforward and appears tolerant of interobserver variability. A number of discontinuous COW variants become more prevalent with age, perhaps from atherosclerotic occlusive disease. There was no association between COW variants, gender, aneurysm location or MRI disease status.
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