Program Results

Introduction to the event

In this study, we analysed the blood pressure and blood flow in 56 human brain anatomies. The imaging data were previously segmented, and the full geometrical details computed, enabling a haemodynamic model of blood flow to be constructed, considering both static and dynamic flow patterns. The dynamic model enabled us to calculate the response of the system in terms of just two non-dimensional numbers, the Womersley number and a wall time constant, using a matrix formulation for the first time that is quick to compute in large networks.

The pressure distributions showed the gradual decrease in pressure towards the capillary bed, as expected, and the static flow fields were found to be good agreement with the literature. The dynamic flow field showed that the phase shift at the cardiac frequency is very small, indicating that the large vessels essentially act in quasi-steady state. This is an important simplification for future models of the cerebral circulation.

The changes in the network flow with age for both male and female subjects were calculated, showing that there is a consistent drop with age, which is in good agreement with other experimental studies in the literature. This cannot be explained by pure vasodilation and thus indicates that there are significant physiological effects of ageing on the geometrical properties of the network.

The results from this study are now being used in a follow-up, performed in collaboration with Tohoku University, Japan, to develop a statistical model of these large vascular networks. Such statistical models will play an important role in the development of virtual populations of the cerebral vasculature. These virtual populations can be used to simulate cerebral diseases such as stroke and to interpret imaging data acquired clinically, leading to a better understanding of the cerebral vasculature in both health and disease.

Simulation results of blood pressure and blood flow in the large blood vessels of a human brain. Blood pressure shown in (a) axial view; (b) coronal view; (c) sagittal view. Blood flow (static) shown in (d) axial view; (e) coronal view; (f) sagittal view. Blood flow (dynamic) shown in (g) axial view; (h) coronal view; (i) sagittal view.