Optimizing imaging time for improved performance in oncology PET studies

The potential for improving the diagnostic performance of static positron imaging tomography (PET) by judiciously choosing optimum post-injection imaging times is investigated.

Dynamic and whole-body scan data, from 2-deoxy-2-[18F]fluoro-D-glucose (FDG) oncological studies, are analyzed for changing standardized uptake value (SUV) behavior with increasing post-injection times at either single- or multiple-bed positions. Model-based interpretations address d(SUV)/dt, shown to correlate with SUV, and the contrast ratio for a tumor and its surroundings. A method for correcting measurements to a standardized time is given.

Both data and model-based equations suggest that starting data acquisition later than the average 55 +/- 15 (SD) minutes post-injection reported in the FDG literature can improve contrast ratios. Considerations for choosing an optimum time from a clinical standpoint are listed.

It is concluded that the appropriate time for each particular protocol can be found with the aid of the information presented here. True optimization, however, remains a complex issue.