Special Challenges in PET Imaging of Ectothermic Vertebrates

The bulk of biomedical positron emission tomography (PET)-scanning experiments are performed on mammals (ie, rodents, pigs, and dogs), and the technique is only infre-quently applied to answer research questions in ectothermic vertebrates such as fish, amphibians, and reptiles. Nevertheless, many unique and interesting physiological characteristics in these ectothermic vertebrates could be addressed in detail through PET. The low metabolic rate of ectothermic animals, however, may compromise the validity of physiological and biochemical parameters derived from the images created by PET and other scanning modalities. Here, we review some of the considerations that should be taken into account when PET scanning fish, amphibians, and reptiles. We present specific results from our own experiments, many of which remain previ-ously unpublished, and we draw on examples from the literature. We conclude that knowledge on the natural history and physiology of the species studied and an under-standing of the limitations of the PET scanning techniques are necessary to avoid the design of faulty experiments and erroneous conclusions. Semin Nucl Med 53:577-585 & COPY; 2023 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)