Using Procedurally Expanded Discrete Cerebral Vasculature with a Vascular-Porous Model to Simulate Perfusion and Temperature Effects Following Ischaemic Stroke

Modelling the flow and temperature effects after ischaemic stroke can be shown to require vasculature with a level of detail not obtainable from conventional imaging techniques. We have developed a method to augment the obtainable cerebral vasculature with additional procedurally generated vasculature, creating a 1D hybrid tree for the arteries and veins. Procedural generation is weighted by the positions of arterial territories and tissue type. It creates vessel networks which functions according to clinical expectations. This is then combined with a 3D porous tissue and our existing Vascular-Porous (VaPor) model to fully simulate the blood flow and temperature distributions in the cerebral geometry, including satisfactory simulation of the ischaemic region. The resulting perfusion profile, including occlusion geometry, and temperature profile are calculated by solving the mass, momentum and energy equations. Good visual agreement is seen between the perfusion profiles obtained with VaPor and those from in-vivo imaging of stroke, including the presence of penumbral tissue. Simulation of stroke allows obstruction of any arterial vessel segment within the base tree and observing the effects. These results show that there can be significant variation in the perfusion after stroke, even for a similarly placed obstruction. Applying our model shows temperature rises in the affected region immediately after stroke, of the order of 0.5 °C. Crucially, our model also indicates that, dependant on location, these temperature profiles can be influenced by external cooling. Meaning that direct brain cooling via the scalp could be more effective than previously thought.