COMPLEX HIERARCHICAL MODELING OF THE DYNAMIC PERFUSION TEST : APPLICATION TO LIVER

We propose a multicompartment model of hepatic blood perfusion that serves as a form of feedback for numerical simulations of dynamic CT investigation. The blood flow in the human liver can be characterized at several scales, using different models for each of them. In this paper, we focus on two levels: The flow in branching vessels with lumen diameters above 2 mm is described by a simple 1D model based on the Bernoulli equation completed with correction terms representing the local friction loss. This flow model is coupled through point sources/sinks with a 3D model describing multicompartment flows in tissue parenchyma. The compartments in the tissue parenchyma are associated with segments and hierarchies that confine the flow to a certain subdomain within the organ and respect the complexity of flow distribution according to the branching vascular trees of the portal and hepatic veins. Because the present research is motivated by the modeling of liver perfusion with the purpose to enable an improved analysis of CT scans, the model of contrast fluid propagation in each compartment is introduced as well. In this way, the time-space distribution of the so-called tissue density can be computed and compared with the measured data obtained form the CT scans.