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Intracranial Atherosclerotic Disease Distribution Across Circle of Willis Segments: Insights from CREST-H
Pranjal Rai1, John Huston2, Thomas G Brott1
1From the Mayo Clinic, Rochester (P.R., J.H., R.D.B., G.L.), Minnesota, USA; Mayo Clinic (T.G.B., J.F.M.), Jacksonville, Florida, USA; University of Alabama at Birmingham (L.E., G.H., R.L.), Birmingham, Alabama, USA; Medical University of South Carolina (J.H.V.), Charleston, South Carolina, USA; University of Maryland School of Medicine (B.K.L.), Baltimore, Maryland, USA; Yale University (C.M.-H.), New Haven, Connecticut, USA; Cone Health (D.V.H.), Greensboro, North Carolina, USA; Cooper University Health Care (T.G.J.), Camden, New Jersey, USA; Kaiser Permanente (N.S.), Los Angeles, California, USA; Maine Health (R.D.E.), Portland, Maine, USA; University of California (D. S.L.), Los Angeles, Los Angeles, California, USA and Columbia University Irving Medical Center (R.S.M.), New York, New York, USA.
Insights
Intracranial atherosclerotic disease (ICAD) is common, particularly in the internal carotid arteries (ICAs). Associations exist between ICAD in different Circle of Willis (CoW) segments, informing future research on stroke risk.
Area of Science:
- Neurology
- Vascular Medicine
- Radiology
Background:
- The Circle of Willis (CoW) is a critical collateral pathway influencing cerebral blood flow.
- Its anatomy can affect intracranial flow patterns, especially with atherosclerotic disease.
- Understanding intracranial atherosclerotic disease (ICAD) distribution is vital for managing cerebrovascular risks.
Purpose of the Study:
- To describe the distribution of ICAD within the CoW.
- To evaluate associations of ICAD presence across CoW vessel segments.
- To analyze data from the Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis - Hemodynamics (CREST-H) cohort.
Main Methods:
- Retrospective analysis of 252 patients from the CREST-H trial.
- Time-of-flight MR angiography (TOF-MRA) used to assess intracranial arterial narrowing and irregularity.
- CoW categorization by completeness and pattern (Ayre's classification); Phi-coefficient for association analysis.
Main Results:
- ICAD most frequent in right (69.4%) and left (67.1%) intracranial ICAs.
- Partially complete CoW observed in 73.8% of patients.
- Significant associations found between right ICA and right ACA, and between contralateral vessels (e.g., right/left ICA, PCA/ACA).
Conclusions:
- ICAD is prevalent in the CREST-H cohort, predominantly in intracranial ICAs.
- Observed associations between ipsilateral and contralateral CoW segments.
- Findings provide preliminary data for future studies on ICAD distribution in patients with carotid atherosclerosis.
Background:
The Circle of Willis (CoW) is an important collateral pathway, and its anatomy may influence intracranial flow patterns in the setting of atherosclerotic disease. This study describes the distribution of intracranial atherosclerotic disease (ICAD) and evaluates associations between ICAD presence across CoW vessel segments in the Carotid Revascularization and Medical Management for Asymptomatic Carotid Stenosis - Hemodynamics (CREST-H) cohort.
Methods:
This retrospective analysis included 252 patients from the CREST-H trial with baseline Time-of-flight MR angiography (TOF-MRA) suitable for evaluation. TOF-MRA was used as a luminal surrogate to assess intracranial arterial narrowing and irregularity, rather than as a direct plaque-imaging technique. Intracranial arterial segments were assessed for luminal abnormalities compatible with ICAD, and the CoW was categorized based on circle completeness and anatomical pattern using Ayre's classification. Phi-coefficient was used to evaluate associations in ICAD presence across vessel segment pairs.
Results:
ICAD was most frequently observed in the right (69.4%) and left (67.1%) intracranial ICA, followed by anterior and posterior circulation CoW segments. Complete, partially complete, and fully incomplete CoW was identified in 17.5%, 73.8%, and 8.7% of patients, respectively. Pairwise associations in ICAD presence were observed between the right ICA and right ACA (ϕ = 0.25, p < 0.001) and between contralateral paired vessels, including right and left ICA, PCA and ACA (all p < 0.001). No correlation was found between left ICA and left ACA (ϕ = 0.10, p = 0.08).
Conclusions:
In the atherosclerosis-enriched CREST-H cohort, ICAD was common and was most frequently seen in intracranial ICAs. Associations in ICAD presence were observed between selected ipsilateral and contralateral CoW vessel pairs. These findings are descriptive and may help provide preliminary data for future studies of intracranial atherosclerotic distribution in patients with carotid atherosclerotic disease.
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