Issues of Quantitative Metabolic Brain Imaging with Small Animal PET in Mice

Positron emission tomography (PET) allows imaging of molecular and physiological events in living subjects. Recent technical advances have made it possible to use PET for small animals. A major advantage of small animal PET studies compared to necropsy studies is that the former allows longitudinal within-subject design. Fully quantitative PET studies require information on the time course of tracer delivery to the tissue. In practical terms, one disadvantage of small animal PET imaging is the need to control the animal's motion during the study in order to obtain good quantitative invivo dynamic imaging results. Thus, animals must be either physically restrained or placed under anesthesia. Anesthesia is known to have significant effects on the central nervous, cardiovascular and respiratory systems. Restraining devices lead to extremely high stress levels, which can create conditions that poorly reflect normal physiology of an animal. In this paper, we assess feasibility and limitations of quantitative metabolic brain imaging with small animal PET in mice based on our recent published papers using [18F]FDG and small animal PET. Future perspectives in quantitative metabolic brain imaging with PET in small animals are also discussed.