Image normalization strategies for organ specific models of functional uptake in FDG-PET /CT

We are investigating techniques to develop organ specific models of normal functional Positron Emission Tomography (PET) uptake. A key issue in the development of models of functional uptake is the appropriate normalization of the PET uptake across multiple studies. It is well known that the tracer uptake in PET is subject is a range of variations including protocols and scanners, reconstruction algorithm as well as biological effects. In this study, we investigate and report results of normalization strategies for a group of organs. In particular, we evaluate the performance of reference tissue normalization strategies applied to our problem and propose a novel normalization strategy that estimates the normal uptake for a particular organ from that of a number of reference tissue regions that may be assumed to be disease-free. Results from the quantitative analysis indicate that a normalisation method using weighted contribution from a number of reference regions perform better than the best normalisation using a single reference region (liver), and show equivalent performance of both normalisation strategies for the abnormal voxel classification experiment.