Challenges and chances of preclinical and animal experimental PET imaging

Positron-emission-tomography (PET) is a nuclear imaging technique that permits the spatial and temporal distribution of compounds labeled with a positron-emitting radionuclide to be determined noninvasively. Positron-labeled compounds (tracers) have been synthesized to target a range of specific markers and pathways. Small animal PET (i.e. mice, rats, hamsters) has undergone a major evolution. This has been driven by technical improvements and increasing interest of pharmaceutical companies. The focus of the method has shifted towards the quantification of the physiological parameters necessary to use this technique for kinetic modeling of tracers. Methods for minimising the number of animals used for experiments and minimising animal suffering have to be considered (concept of 3R: replacement, reduction and refinement) to provide more humane animal research. In this review, we will give an overview of how the technique can be used to study diseases, to evaluate therapies or new drugs and to gain inside into molecular processes in vivo.