Figure 8. Figure illustrating the basic compartments involved in pharmacokinetic modelling of intravenous contrast distribution. Movements of contrast between compartments will be governed by the ratio of the contrast concentrations between those compartments and by the local blood flow and the surface area and permeability of the capillary endothelium to contrast agent (represented by the thickness of the connecting arrows). The composite transfer coefficient for contrast between blood and the tissue of interest is represented as k^trans.