DCE-MRI Non-Rigid Kidney Registration

Introduction: Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is a very promising method for noninvasive assessment of renal function such as renal perfusion or glomular filtration rate. The acquisition of DCE-MRI for that purpose is usually performed during free breathing because the scan duration, necessary for data analysis, is typically in the order of several minutes. The physiological motion is therefore clearly visible in the time series data, measured with a snapshot technique. For a pixel-by-pixel analysis (e.g. perfusion map) or small ROI’s (cortex), the data suffer from severe noise like artifacts (see Fig. 1a). Furthermore, the motion leads to a blurring and a bias of derived parameters of the individual compartments. Image registration is therefore a very important preprocessing step for the analysis of DCE-MRI data from moving organs. However, image registration is a challenging task due to the signal enhancement induced by contrast media [1, 2]. To overcome that problem, an image registration procedure was implemented which derives a template image series with the underlying signal time course. The original dynamic time series (source images) is registered by elastic registration to this virtual template. It is demonstrated that the algorithm is able to reduce motion artifacts to a high extend and allows a more differentiated analysis of several kidney tissue types such as renal cortex and renal medulla.