Where the exception becomes the rule: MR and CT Angiography in the assessment of anatomic variants and anomalies of the circle of Willis

Congress:

ECR 2020

Poster Number:

C-10105

Type:

Educational Exhibit

Keywords:

Not applicable, Congenital, Normal variants, Education, MR-Angiography, MR, CT-Angiography, Vascular, Neuroradiology brain, Anatomy, Neuro

Authors:

C. I. Buleandra, C. Pop; Cluj-Napoca/RO

DOI:

10.26044/ecr2020/C-10105

DOI-Link:

https://dx.doi.org/10.26044/ecr2020/C-10105

Fig. 1: 3D TOF: circle of Willis: anterior communicating artery (blue arrow), anterior...

Fig. 2: Classification of normal variants of the circle of Willis

Fig. 3: (a) 2D TOF, (b) MIP TOF and (c) 3D TOF: hypoplasia of right A1 segment (blue...

Fig. 4: 3D MDCT angiography: hypoplasia of left P1 segment (blue arrow) associated with...

Learning objectives

To review the development and normal anatomy of the vessels comprising the circle of Willis To get a better understanding of the appearances of normal variants To illustrate the spectrum of the most common variants using Computed Tomography (CT) and Magnetic Resonance (MR) angiography To emphasize the clinical significance of these variations

Background

The circle of Willis represents an anastomotic arterial network localized at the base of the brain. This anastomotic structure has a crucial role in case of occlusion or important stenosis of one of the arterial branches providing collateral flow to the affected portions of the brain. 1. Embryology and development of the circle of Willis The development of the intracranial arteries begins at 24 days with the development of the internal carotid artery (ICA) from the 3rd branchial arch arteries and the distal segments of...

Findings and procedure details

We will discuss the most common variations of the circle of Willis through a case base review following a proposed classification (Fig.2). The normal variations will be illustrated through highlighted cases while stressing the relevant associated clinical features using: - CT Angiography: 3D reconstructions and MIPs - MR Angiography: 2D, 3D-TOF and contrast enhanced MRA 1. Variations in morphology Hypoplasia is defined as a vascular anomaly in which the vessel’s caliber is less than 0,8 mm [3]. Hypoplasia can affect all the components of the...

Conclusion

Normal variants of the circle of Willis are the exception, not the rule. Recognizing normal variations of the intracranial arteries sometimes carries the same clinical relevance as identifying the pathology.

Personal information and conflict of interest

C. I. Buleandra; Cluj/RO - nothing to disclose C. Pop; Cluj/RO - nothing to disclose

References

1. Menshawi K, Mohr JP, Gutierrez J. A functional perspective on the embryology and anatomy of the cerebral blood supply. J Stroke. 2015;17(2):144–58. 2. Osborn AG, Salzman KL, Jhaveri MD, Barkovich AJ. Diagnostic imaging: brain. Elsevier. 2017:201. 3. Chen HW, Yen PS, Lee CC, Chen CC, Chang PY, Lee SK, et al. Magnetic resonance angiographic evaluation of circle of Willis in general population: a morphologic study in 507 cases. Chin J Radiol. 2004;29(5):223-9. 4. Krabbe-Hartkamp MJ, Van der Grond J, De Leeuw FE, De Groot...