Anatomical variations of the circle of Willis: evaluation with CT angiography
Objectives: The aim of this study was to investigate anatomic variants and anomalies of the circle of Willis using computedtomography angiography (CTA).Methods: CTA images of 770 patients obtained from Tepecik Training and Research Hospital between January 2012 to January2017 were retrospectively reviewed to identify the anatomical vascular variations of the circle of Willis.Results: After exclusion, 751 patients (348 females, 403 males, mean age 54.6 years, range 18–90 years) were enrolled into thestudy. The anatomical variations related to the posterior communicating artery (PcoA) were the most common, whereas anatomicalvariations related to the middle cerebral artery (MCA) were the least common variations among arteries. Hypoplasia of theA1 segment was the most common (14.6%) variation of the anterior cerebral artery (ACA) and fenestration of this artery wasthe least common variation (1,06%) observed only in A1 segment. Bilateral absence of the PcoA was seen in 27.56% of thepatients. Fenestration was more commonly detected in anterior communicating artery (AcoA) (10.12%), followed by MCA(1.06%), ACA (1,06%) and PCA (0.67%). Duplication was the least common variation which was detected in MCA, AcoA andPcoA.Conclusion: Arterial variations of the circle of Willis are not rare and can be non-invasively evaluated using CTA.
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- 1. Dimmick SJ, Faulder KC. Normal variants of the cerebral circulation
at multidetector CT angiography. Radiographics 2009;29:1027–
43.
- 2. van Rooij SB, van Rooij WJ, Sluzewski M, Sprengers ME.
Fenestrations of intracranial arteries detected with 3D rotational
angiography. AJNR Am J Neuroradiol 2009;30:1347–50.
- 3. Osborn AG. Diagnostic cerebral angiography (2nd ed). Philadelphia,
PA: Lippincott Williams & Wilkins; 1999.
- 4. Komiyama M, Nakajima H, Nishikawa M, Yasui T. Middle cerebral
artery variations: duplicated and accessory arteries. AJNR Am J
Neuroradiol 1998;19:45–9.
- 5. Parmar H, Sitoh YY, Hui F. Normal variants of the intracranial circulation
demonstrated by MR angiography at 3T. Eur J Radiol 2005;
56:220–8.
- 6. Jayaraman MV, Mayo-Smith WW, Tung GA, Haas RA, Rogg JM,
Mehta NR, Doberstein CE. Detection of intracranial aneurysms:
multi-detector row CT angiography compared with DSA. Radiology
2004;230:510–8.
- 7. Pekcevik Y, Pekcevik R. Variations of the cerebellar arteries at CT
angiography. Surg Radiol Anat 2014;36:455–61.
- 8. Nussbaum ES, Defillo A, Janjua TM, Nussbaum LA. Fenestration of
the middle cerebral artery with an associated ruptured aneurysm. J
Clin Neurosci 2009;16:845–7.
- 9. Songur A, Gonul Y, Ozen OA, Kucuker H, Uzun I, Bas O, Toktas
M. Variations in the intracranial vertebrobasilar system. Surg Radiol
Anat 2008;30:257–64.
- 10. Kiro¤lu Y, Karabulut N, Oncel C, Akdogan I, Onur S. Bilateral symmetric
junctional infarctions of the cerebellum: a case report. Surg
Radiol Anat 2010;32:509–12.
- 11. de Gast AN, van Rooij WJ, Sluzewski M. Fenestrations of the anterior
communicating artery: incidence on 3D angiography and relationship
to aneurysms. AJNR Am J Neuroradiol 2008;29:296–8.
- 12. Reis CV, Zabramski JM, Safavi-Abbasi S, Hanel RA, Deshmukh P,
Preul MC. The accessory middle cerebral artery: anatomic report.
Neurosurgery 2010;66:E1217.
- 13. Hamidi C, Bükte Y, Hattapo¤lu S, Ekici F, Tekbafl G, Önder H,
Gümüfl H, Bilici A. Display with 64-detector MDCT angiography of
cerebral vascular variations. Surg Radiol Anat 2013;35:729–36.
- 14. Kashiwazaki D, Kuroda S, Horiuchi N, Takahashi A, Asano T,
Ishikawa T, Iwasaki Y. Ruptured aneurysm of bihemispheric anterior
cerebral artery bifurcation: case report. No Shinkei Geka 2005;33:
383–7.
- 15. Cinnamon J, Zito J, Chalif DJ, Gorey MT, Black KS, Scuderi DM.
Aneurysm of the azygos pericallosal artery: diagnosis by MR imaging
and MR angiography. AJNR Am J Neuroradiol 1992;13:280–2.
- 16. Bayrak AH, Senturk S, Akay HO, Ozmen CA, Bukte Y, Nazaroglu
H. The frequency of intracranial arterial fenestrations: a study with
64-detector CT-angiography. Eur J Radiol 2011;77:392–6.
- 17. van der Lugt A, Buter TC, Govaere F, Siepman DA, Tanghe HL,
Dippel DW. Accuracy of CT angiography in the assessment of a
fetal origin of the posterior cerebral artery. Eur Radiol 2004;14:
1627–33.
- 18. van Overbeeke JJ, Hillen B, Tulleken CA. A comparative study of the
circle of Willis in fetal and adult life: the configuration of the posterior
bifurcation of the posterior communicating artery. J Anat 1991;
176:45–54.
- 19. van Raamt AF, Mali WP, van Laar PJ, van der Graaf Y. The fetal
variant of the circle of Willis and its influence on the cerebral collateral
circulation. Cerebrovasc Dis 2006;22:217–24.