Circle of Willis Intracranial Artery Classification and Quantification Challenge

Bifurcations of the arteries of the circle of Willis (CoW; an arterial anastomotic circle providing blood to the brain) are a typical location for unruptured, intracranial aneurysms (UIAs) to develop. UIAs are relatively common, with an estimated prevalence of 3% in the general population. Rupture of an UIA leads to aneurysmal subarachnoid hemorrhage (ASAH), a severe subtype of stroke with significant socio-economic burden. Patients who survive an ASAH often require lifelong rehabilitation or nursing home care [1]. UIAs are more frequently diagnosed in patients with a positive family history for ASAH [2]. This indicates that there are genetic factors that contribute to the development of UIAs. Long-term serial screening for UIAs in first-degree family members of ASAH patients is currently recommended with UIAs identified in 11% during first and 8% during follow-up screening [3]. However, accurate risk prediction models to identify individuals at the highest risk of UIAs at screening are still lacking. Variation in CoW configuration, bifurcation angles and diameters of CoW arteries are one of the few established morphological imaging markers predictive of UIA development [4]. The anatomical variation in CoW configuration across individuals is large: absent, hypoplastic or additional arteries are seen in approximately 70% of individuals [5]. With the use of 3D time-off-flight magnetic resonance angiography (TOF-MRA), the CoW can be imaged. Automated methods to assess CoW configurations and artery morphology would facilitate the search for new risk factors for UIA development in large patient cohorts. The CROWN challenge aims to find automatic methods for both classification of the CoW configuration (Task 1) and quantification of the major CoW artery diameters and bifurcation angles (Task 2). For this challenge, we have 600 TOF-MRA scans available from healthy individuals. Measurements of the CoW configuration variant, CoW artery diameters and CoW bifurcation angles are provided, created by three observers. [1] Nieuwkamp, Dennis J., et al. "Changes in case fatality of aneurysmal subarachnoid haemorrhage over time, according to age, sex, and region: a meta-analysis." The Lancet Neurology 8.7 (2009): 635-642. [2] Ruigrok, Ynte M., Gabriël JE Rinkel, and Cisca Wijmenga. "Genetics of intracranial aneurysms." The lancet neurology 4.3 (2005): 179-189. [3] Bor, A. Stijntje E., et al. "Long-term, serial screening for intracranial aneurysms in individuals with a family history of aneurysmal subarachnoid haemorrhage: a cohort study." The Lancet Neurology 13.4 (2014): 385-392. [4] Kancheva, Angelina K., Birgitta K. Velthuis, and Ynte M. Ruigrok. "Imaging markers of intracranial aneurysm development: A systematic review." Journal of Neuroradiology (2021). [5] Eftekhar, Behzad, et al. "Are the distributions of variations of circle of Willis different in different populations?–Results of an anatomical study and review of literature." BMC neurology 6.1 (2006): 1-9