Many relevant parameters of the vascular morphology and function are beneath the spatial resolution of magnetic resonance (MR) imaging methods. However, they can affect the image contrast, e.g. when they are labelled by specific contrast agents or when sophisticated imaging tools are used. The question remains, how to gain information about the biological parameters from the image contrast. This task may be solved by the development of appropriate mathematical models. The aim of this project is to develop such models which determine parameters of the cardiac microcirculation and of cellular/ molecular processes from the MR image contrast.