Asymptomatic small intracranial aneurysms affect about 1 in 50 people and are often considered at a low risk of rupture. There are no effective hemodynamic parameters accurately predicting the evolution of small aneurysms. Three dimensional vortex motion is observed in aneurysms which reflects the hemodynamic environment and potentially impact the development of small aneurysms. We propose an approach to describe the three dimensional main vortex motion as a whole inside small aneurysms based on 4D Flow MRI at 7 Tesla. This approach defines the high vortex motion region and gives the direction of the main vortex motion and its center.