Skip to main content
Log in

Anterior cerebral artery variations detected by MR angiography

Neuroradiology Aims and scope Submit manuscript

Cite this article



From anatomical and angiographic studies, it is well known that there are several variations of the anterior cerebral artery (ACA). However, ACA variations have rarely been studied by magnetic resonance (MR) angiography. The purpose of this study was to investigate not only the type, location, configuration, and incidence of ACA variations, but also coexisting arterial pathology such as aneurysms detected by cranial MR angiography.


We retrospectively reviewed cranial MR angiography images of 891 patients at our institution. All images were obtained with one of two 1.5-T scanners using the three-dimensional time-of-flight technique. Maximum intensity projection (MIP) images in the horizontal rotation view were displayed stereoscopically. We reviewed these horizontal MIP images, inferosuperior MIP images, and source images, and identified variations of the ACA.


We found 50 instances (5.6%) of unilateral A1 segment aplasia, 27 (3.0%) of three A2 segments, 18 (2.0%) of an unpaired A2 segment, and 11 (1.2%) fenestrations of the A1 and/or A2 segment. Seven anterior communicating artery (ACoA) aneurysms and one ACA territory embolic infarction were found among the 50 patients with unilateral A1 segment aplasia. One ACoA aneurysm and one pericallosal infarction were found in the 27 patients with three A2 segments. Two distal ACA aneurysms were detected among the 18 patients with an unpaired A2 segment. No associated aneurysm was seen at the fenestrations.


Although the clinical significance of ACA variations is usually minor, an associated aneurysm is found relatively frequently. Thus, recognizing ACA variations during the interpretation of cranial MR angiograms is important.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7


  1. Baptista AG (1963) Studies on the arteries of the brain. II. The anterior cerebral artery: some anatomic features and their clinical implications. Neurology 13:825–835

    PubMed  CAS  Google Scholar 

  2. Sanders WP, Sorek PA, Mehta BA (1993) Fenestration of intracranial arteries with special attention to associated aneurysms and other anomalies. AJNR Am J Neuroradiol 14:675–680

    PubMed  CAS  Google Scholar 

  3. Krabbe-Hartkamp MJ, van der Grond J, de Leeuw FE et al (1998) Circle of Willis: morphologic variation on three-dimensional time-of-flight MR angiograms. Radiology 207:103–111

    PubMed  CAS  Google Scholar 

  4. Wollschlaeger G, Wollschlaeger PB (1974) The circle of Willis. In: Newton TH, Potts DG (eds) Radiology of the skull and brain angiography, vol. 2. Mosby, St. Louis, pp 1171–1201

    Google Scholar 

  5. Stehbens WE (1963) Aneurysms and anatomical variation of cerebral arteries. Arch Pathol 75:45–64

    PubMed  CAS  Google Scholar 

  6. Yamaguchi K, Uchino A, Sawada A, Takase Y, Kuroda Y, Kudo S (2004) Bilateral anterior cerebral artery territory infarction associated with unilateral hypoplasia of the A1 segment: report of two cases. Radiat Med 22:422–425

    PubMed  Google Scholar 

  7. Yanaka K, Shirai S, Shibata Y, Nose T (2000) Ruptured aneurysm at the origin of the median artery of the corpus callosum associated with accessory middle cerebral artery. Case report. Neurol Med Chir (Tokyo) 40:511–514

    Article  CAS  Google Scholar 

  8. Huber P, Braun J, Hirschmann D, Agyeman JF (1980) Incidence of berry aneurysms of the unpaired peri-callosal artery: angiographic study. Neuroradiology 19:143–147

    Article  PubMed  CAS  Google Scholar 

  9. Hernesniemi J, Tapaninaho A, Vapalahti M, Niskanen M, Kari A, Luukkonen M (1992) Saccular aneurysms of the distal anterior cerebral artery and its branches. Neurosurgery 31:994–999

    Article  PubMed  CAS  Google Scholar 

  10. Cinnamon J, Zito J, Chalif DJ et al (1992) Aneurysm of the azygos pericallosal artery: diagnosis by MR imaging and MR angiography. AJNR Am J Neuroradiol 13:280–282

    PubMed  CAS  Google Scholar 

  11. Topsakal C, Ozveren MF, Erol FS, Cihangiroglu M, Cetin H (2003) Giant aneurysm of the azygos pericallosal artery: case report and review of the literature. Surg Neurol 60:524–533

    Article  PubMed  Google Scholar 

  12. Ito J, Washiyama K, Kim CH, Ibuchi Y (1981) Fenestration of the anterior cerebral artery. Neuroradiology 21:277–280

    Article  PubMed  CAS  Google Scholar 

  13. Taylor R, Connolly ES Jr, Duong H (2000) Radiographic evidence and surgical confirmation of a saccular aneurysm on a hypoplastic duplicated A1 segment of the anterior cerebral artery. Case report. Neurosurgery 46:482–484

    Article  PubMed  CAS  Google Scholar 

Download references


We thank Kaori Ayabe for her assistance in the preparation of the manuscript.

Conflict of interest statement

We declare that we have no conflict of interest.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Akira Uchino.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Uchino, A., Nomiyama, K., Takase, Y. et al. Anterior cerebral artery variations detected by MR angiography. Neuroradiology 48, 647–652 (2006).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: