MicroPET® R4 neuro-imaging in rats and post-mortem measures

Small animal studies performed on dedicated small animal scanners may be technically very demanding and, especially in the case of brain receptor studies, susceptible to confounds such as anesthesia and tracer mass effect. In addition, studies might require a large number of animals to achieve statistically meaningful results. Here we investigated accuracy and limitations of PET data compared to post-mortem studies and techniques to reduce scanning times in the investigations of the dopaminergic system in a rat model of Parkinson´s disease (PD) using a microPET^® R4. We found that (i) different anesthetics influence tracer kinetics in a tracer specific manner and thus must be taken into account, especially when an intertracer comparison is performed, (ii) for selected tracers it might be possible to reduce scanning times and still obtain reliable and biologically meaningful information from the data, (iii) mass effect studies indicate that with a shorter scanning protocol it is indeed possible to perform at least two scans with the same tracer delivery thus significantly reducing the cost of scanning without affecting the accuracy of the results. Taken together these results provide some guidance in achieving highly time and cost efficient scanning protocols leading to biologically accurate and meaningful results.