The Circle of Willis (CoW) is an important network of arteries connecting
major circulations of the brain. Its vascular architecture is believed to
affect the risk, severity, and clinical outcome of serious neuro-vascular
diseases. However, characterizing the highly variable CoW anatomy is still a
manual and time-consuming expert task. The CoW is usually imaged by two
angiographic imaging modalities, magnetic resonance angiography (MRA) and
computed tomography angiography (CTA), but there exist limited public datasets
with annotations on CoW anatomy, especially for CTA. Therefore we organized the
TopCoW Challenge in 2023 with the release of an annotated CoW dataset and
invited submissions worldwide for the CoW segmentation task, which attracted
over 140 registered participants from four continents. TopCoW dataset was the
first public dataset with voxel-level annotations for CoW's 13 vessel
components, made possible by virtual-reality (VR) technology. It was also the
first dataset with paired MRA and CTA from the same patients. TopCoW challenge
aimed to tackle the CoW characterization problem as a multiclass anatomical
segmentation task with an emphasis on topological metrics. The top performing
teams managed to segment many CoW components to Dice scores around 90%, but
with lower scores for communicating arteries and rare variants. There were also
topological mistakes for predictions with high Dice scores. Additional
topological analysis revealed further areas for improvement in detecting
certain CoW components and matching CoW variant's topology accurately. TopCoW
represented a first attempt at benchmarking the CoW anatomical segmentation
task for MRA and CTA, both morphologically and topologically.

通过提供带有注释的 CoW 数据集和组织全球性的 CoW 切割任务，TopCoW 挑战赛成功地成为首个以形态学和拓扑学来评估 MRA 和 CTA 的 CoW 解剖分割任务的基准测试，为研究 CoW 的解剖学特征及其与神经血管性疾病的风险、严重程度和临床结果的关系提供了重要参考。