Neurointervention.  2021 Jul;16(2):190-193. 10.5469/neuroint.2021.00136.

Usefulness of Computed Tomographic Perfusion Imaging for Appropriate Diagnosis of Acute Cerebral Vessel Occlusion in Case of Anatomic Variations of the Circle of Willis

• James JC
• Richter D
• Tomaske L
• Schneider R
• Lukas C
• Kaemmerer F
• Gold R
• Krogias C

• KMID: 2517747
• DOI: http://doi.org/10.5469/neuroint.2021.00136

Abstract

Mechanical thrombectomy (MT) is an effective treatment in patients with acute ischemic stroke (AIS) due to emergent large-vessel occlusion in the anterior circulation. Occlusion of the anterior cerebral artery (ACA) affects up to 15% of these patients. Here we report a case of an elderly patient with an successful MT of an embolic A2-segment occlussion with the anatomic variation of a triplication. Triplication of ACA is a rare anatomical variation, and the occlusion could have been easily overlooked in case of not performing the CT-perfusion (CTP) sequences. As anatomical variations of the circle of Willis are present in most subjects, CTA alone might be limited in the acute setting, particularly for young residents performing the first view on call. This case highlights the importance of including CTP in the initial CT-diagnostic algorithm in AIS patients who are basically eligible for recanalization therapies, irrespective of inconspicuous initial findings in CTA.

Keyword

Stroke; Thrombectomy; Perfusion imaging

Figure

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  Fig. 1. Cranial images of an elderly patient. (A) Non-contrast scan with no early ischemic signs. (B) CTA with no occlusion of intracerebral arteries on first view. (C) CTP sequence. Mean transit time (MTT) delayed in the area of the right ACA, followed by a congruent cerebral blood flow (CBF) and cerebral blood volume (CBV) mismatch. (D) Interventional angiography of the right ACA before MT and verification of a triplication (arrow). (E) Interventional angiography of the right ACA after MT. CTA, computed tomographic (CT)-angiography; CTP, CT-perfusion; ACA, anterior cerebral artery; MT, mechanical thrombectomy.

Reference

1. Tsivgoulis G, Safouris A, Krogias C, Arthur AS, Alexandrov AV. Endovascular reperfusion therapies for acute ischemic stroke: dissecting the evidence. Expert Rev Neurother. 2016; 16:527–534.

2. Pfaff J, Herweh C, Pham M, Schieber S, Ringleb PA, Bendszus M, et al. Mechanical thrombectomy of distal occlusions in the anterior cerebral artery: recanalization rates, periprocedural complications, and clinical outcome. AJNR Am J Neuroradiol. 2016; 37:673–678.

3. Trepel M. Neuroanatomie: struktur und funktion. 5th ed. München: Urban & Fischer;2011. German.

4. Kang SY, Kim JS. Anterior cerebral artery infarction: stroke mechanism and clinical-imaging study in 100 patients. Neurology. 2008; 70(24 Pt 2):2386–2393.

5. Fawcett E, Blachford JV. The circle of Willis: an examination of 700 specimens. J Anat Physiol. 1905; 40(Pt 1):63.

6. Kapoor K, Singh B, Dewan LI. Variations in the configuration of the circle of Willis. Anat Sci Int. 2008; 83:96–106.

7. Ravikanth R, Philip B. Magnetic resonance angiography determined variations in the circle of Willis: analysis of a large series from a single center. Ci Ji Yi Xue Za Zhi. 2019; 31:52–59.

8. Karatas A, Coban G, Cinar C, Oran I, Uz A. Assessment of the circle of Willis with cranial tomography angiography. Med Sci Monit. 2015; 21:2647–2652.

9. Iqbal S. A comprehensive study of the anatomical variations of the circle of Willis in adult human brains. J Clin Diagn Res. 2013; 7:2423–2427.

10. Ringleb PA, Hamann GF, Röther J, Jansen O, Groden C, Veltkamp R. [Therapy of acute ischemic stroke – recanalisation therapy guideline]. Aktuelle Neurol. 2016; 43:82–91. German.

11. Albers GW, Marks MP, Kemp S, Christensen S, Tsai JP, Ortega-Gutierrez S, DEFUSE 3 Investigators, et al. Thrombectomy for stroke at 6 to 16 hours with selection by perfusion imaging. N Engl J Med. 2018; 378:708–718.

12. Nogueira RG, Jadhav AP, Haussen DC, Bonafe A, Budzik RF, Bhuva P, DAWN Trial Investigators, et al. Thrombectomy 6 to 24 hours after stroke with a mismatch between deficit and infarct. N Engl J Med. 2018; 378:11–21.

13. Thomalla G, Simonsen CZ, Boutitie F, Andersen G, Berthezene Y, Cheng B, WAKE-UP Investigators, et al. MRI-guided thrombolysis for stroke with unknown time of onset. N Engl J Med. 2018; 379:611–622.

14. Jones JD, Castanho P, Bazira P, Sanders K. Anatomical variations of the circle of Willis and their prevalence, with a focus on the posterior communicating artery: a literature review and meta-analysis. [published online ahead of print Jul 26, 2020]. Clin Anat. 2020.

15. Sun C, Xv ZD, Yuan ZG, Wang XM, Wang LJ, Liu C. MSCT diagnosis of aneurysms associated with an unusual variant: atypical triplication anterior cerebral artery. Surg Radiol Anat. 2012; 34:777–780.

16. Ureña FM, Ureña JGM, Almeida S, Rabelo NN, da Silva JR, Mandel M, et al. Anterior communicating artery duplication associated with a triplication of anterior cerebral artery - a rare anatomical variation. Surg Neurol Int. 2020; 11:36.

17. Thomalla G, Gerloff C. Acute imaging for evidence-based treatment of ischemic stroke. Curr Opin Neurol. 2019; 32:521–529.

18. Simonsen CZ, Leslie-Mazwi TM, Thomalla G. Which imaging approach should be used for stroke of unknown time of onset? Stroke. 2021; 52:373–380.

19. Becks MJ, Manniesing R, Vister J, Pegge SAH, Steens SCA, van Dijk EJ, et al. Brain CT perfusion improves intracranial vessel occlusion detection on CT angiography. J Neuroradiol. 2019; 46:124–129.