Tracer Kinetics Modeling Basics: Model Formulation

Introduction With the advances in fast MR imaging techniques, it is possible to monitor the traversal of a MR contrast agent within tissues at short time intervals (of the order of a few seconds or less), thereby allowing the possibility to study blood flow at the tissue level. Dynamic contrastenhanced MRI (DCE MRI) is emerging as a promising approach for in vivo assessment of tissue microcirculation. Quantitative analysis of DCE MRI data has been performed by several approaches, of which the deconvolution approaches are popular among recent studies. Deconvolution analysis of DCE MRI data can in turn be broadly classified into two approaches: (i) numerical (model-independent) deconvolution [1,2] or (ii) model-dependent deconvolution [3-5]. For model-dependent deconvolution, tracer kinetics models (formulated with appropriate microcirculatory parameters) are employed to fit the tissue enhancement curves, and the deconvolution process becomes a parametric fitting process. In this presentation, we illustrate the formulation of such tracer kinetics models by walking through two example models encountered in the literature.