I am a Ph.D student in biomedical engineering and work with prediction of cerebral perfusion, i.e. prediction of the capability of the vasculature to provide the brain tissue with blood. This capability hinges much on the configuration of the circle of Willis, which re-distributes the incoming blood to the separate parts of the brain. At the moment, it is difficult to predict which patient will be harmed, and to what degree, from changed rates of perfusion. We are therefore developing an individual-specific method which combines Magnetic Resonance Imaging and Computed Tomography data with Computational Fluid Dynamics in order to predict pressure distribution in the circle of Willis during extreme vascular conditions, such as surgery.