Techniques necessary for multiple tracer quantitative small-animal imaging studies

Abstract

Introduction: An increasing number and variety of studies on rodent models are being conducted using small-animal positron emission tomography scanners. We aimed to determine if animal handling techniques could be developed to perform routine animal imaging in a timely and efficient manner and with minimal effect on animal physiology. These techniques need to be reproducible in the same animal while maintaining hemodynamic and physiological stability.

Methods: The necessary techniques include (a) the use of inhalant anesthesia, (b) arterial and venous cannulation for multiple tracer administrations and blood sampling, (c) development of small-volume analytic columns and techniques and (d) measurement of the physiological environment during the imaging session.

Results: We provide an example of a cardiac imaging study using four radiotracers (15O-water, 1-[11C]-acetate, 1-[11C]-palmitate and 1-[11C]-glucose) injected into normal rats. Plasma substrates, CO2 production and total metabolites were measured. The animals remained anesthetized over the entire imaging session, and their physiological state was maintained.

Conclusion: The intrastudy stability of the physiological measurements and substrate levels and interstudy reproducibility of the measurements are reported.