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Case Reports
. 2025 Aug 30;47(1):192.
doi: 10.1007/s00276-025-03708-7.

Bilateral anterior cerebral artery-anterior communicating artery junction arterial ring (duplicate origin of the A2) associated with unilateral A1 aplasia diagnosed by magnetic resonance angiography

Akira Uchino  1 , Shunpei Andoh  2
Affiliations
Case Reports

Bilateral anterior cerebral artery-anterior communicating artery junction arterial ring (duplicate origin of the A2) associated with unilateral A1 aplasia diagnosed by magnetic resonance angiography

Akira Uchino et al. Surg Radiol Anat. .

Abstract

Purpose: To describe a case of two arterial rings of the anterior cerebral artery (ACA)-the anterior communicating artery (ACoA) complex diagnosed by magnetic resonance angiography (MRA).

Methods: A 72-year-old woman with a brain tumor underwent cranial magnetic resonance imaging (MRI) and MRA using a 3-Tesla scanner. MRA was performed using a standard 3-dimensional time-of-flight technique.

Results: MRI showed a small convexity meningioma at the right parietal region. MRA showed no pathological lesion. The A1 segment of the left ACA was absent, and bilateral A2 segments were supplied by right ACA. There were two arterial rings at the ACA-ACoA junction, bilaterally. The arterial rings showed triangle configuration, suggesting duplicate origin of the A2 rather than A2 origin fenestration or partial duplication of the ACoA. There was also fetal-type right posterior cerebral artery.

Conclusion: ACA-ACoA complex is reported to be the most frequent site of cerebral arterial fenestration. However, duplicated ACoA, partially duplicated ACoA and other arterial rings of the ACA-ACoA complex were confused and reported as a ACoA fenestration. ACoA true fenestration is rarely reported by MRA. The present case had bilateral ACA-ACoA junction triangular rings, suggesting bilateral duplicate origin of the A2 segment of the ACAs. No similar case has been reported previously in relevant English-language literature. Careful observation of MRA is important for the detection of rare arterial variations. Partial volume-rendering images of MRA is useful for identifying complicated small arterial variations.

Keywords: Anterior cerebral artery; Anterior communicating artery; Arterial ring; Cerebral arterial variations; Fenestration; Magnetic resonance angiography.

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Conflict of interest statement

Declarations. Competing interests: The authors declare no competing interests. Ethical approval and consent to participate: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Consent for publication: The patient signed informed consent regarding publishing his data and figures.

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