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, CO 2 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.