Patterns of Circle of Willis Variants among Patients Undergoing 3 Tesla Magnetic Resonance Angiography at a Tertiary
Subash Thapa1, Rabindra Desar2, Jorina Basnet3
1Department of Radiodiagnosis, Nepal Police Hospital, Mahrajgunj, Kathmandu, Nepal.
Insights
Common variations in the Circle of Willis (CoW) anatomy are prevalent, particularly in older adults. Posterior communicating artery hypoplasia is the most frequent CoW variant, with gender-based differences noted.
Area of Science:
- Neuroimaging
- Vascular Neurology
- Anatomy
Background:
- The Circle of Willis (CoW) is a vital cerebral arterial network.
- Anatomical variations in the CoW can impact cerebrovascular health.
Purpose of the Study:
- To determine the prevalence and patterns of CoW variants.
- To analyze age and gender correlations with CoW variations.
Main Methods:
- Retrospective cross-sectional study of 384 participants.
- 3 Tesla magnetic resonance angiography (TOF MRA protocol) was used.
- Analysis included prevalence, variant patterns, and age/gender correlations.
Main Results:
- A complete CoW was observed in 36.19% of participants; 57.39% had incomplete CoW.
- Anterior anomalies included hypoplasia and A1 segment variations.
- Posterior variants were common, with posterior communicating artery hypoplasia or absence and fetal PCA origin being frequent.
Conclusions:
- Circle of Willis variations are common, especially in older individuals.
- Posterior communicating artery hypoplasia is the most frequent variant.
- Observed variations showed gender-specific differences.
Introduction:
The Circle of Willis (CoW) is a crucial cerebral arterial network, and its anatomical variations may influence cerebrovascular health. This study aimed to determine the prevalence and patterns of CoW variants using 3 Tesla magnetic resonance angiography.
Methods:
This retrospective cross-sectional study was conducted at the Department of Radiology, of a tertiary care center, Nepal, from October 2022 to September 2024 following ethical approval (IRC- 16/2024). Inclusion required adequate 3T MRI imaging using a TOF MRA protocol. (TR 20 ms, TE 3.5 ms, flip angle 15°, slice thickness 0.5 mm). Patients with cerebrovascular disease, prior interventions, or contraindications were excluded. Circle of Willis morphology was analyzed for prevalence, variants, and age/gender correlations using SPSS and Excel.
Results:
The study included 384 participants of which 206 (53.65%) were male. The mean age was 59.20 ± 16.30 years. A complete Circle of Willis (COW) was observed in 139 (36.19%), while 220 (57.39%) were incomplete. Anterior anomalies 126 (32.81%) primarily consisted of hypoplasia, 95 (75.40%) right A1 dominance and absence 24 (19.05%). Posterior variants 345 (89.84%) involved hypoplasia 155 (44.93%) or absence 189 (54.78%) of the posterior communicating artery, with fetal PCA origin in 121 (31.51%).
Conclusions:
This study found common Circle of Willis variations, especially in older adults. Hypoplasia of the posterior communicating artery was the most frequent variation, with differences observed by gender.
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