Variations in the Circle of Willis in a large population sample using 3D TOF angiography: The Tromsø Study

• Published in: PLOS ONE
• Main Authors: Hindenes, Lars Bakke, Håberg, Asta, Johnsen, Liv-Hege, Mathiesen, Ellisiv B., David, Robben, Vangberg, Torgil Riise
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science 2020
• Subjects: Tromsø; Willis
• Online Access: https://hdl.handle.net/11250/2727630; https://doi.org/10.1371/journal.pone.0241373

The main arteries that supply blood to the brain originate from the Circle of Willis (CoW). The CoW exhibits considerable anatomical variations which may have clinical importance, but the variability is insufficiently characterised in the general population. We assessed the anatomical variability of CoW variants in a community-dwelling sample (N = 1,864, 874 men, mean age = 65.4, range 40–87 years), and independent and conditional frequencies of the CoW’s artery segments. CoW segments were classified as present or missing/hypoplastic (w/1mm diameter threshold) on 3T time-of-flight magnetic resonance angiography images. We also examined whether age and sex were associated with CoW variants. We identified 47 unique CoW variants, of which five variants constituted 68.5% of the sample. The complete variant was found in 11.9% of the subjects, and the most common variant (27.8%) was missing both posterior communicating arteries. Conditional frequencies showed patterns of interdependence across most missing segments in the CoW. CoW variants were associated with mean-split age (P = .0147), and there was a trend showing more missing segments with increasing age. We found no association with sex (P = .0526). Our population study demonstrated age as associated with CoW variants, suggesting reduced collateral capacity with older age. publishedVersion © 2020 Hindenes et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.