Variation in PET-CT methodology at academic centers

Learning Objectives In 2005, 8 Imaging Response Assessment Teams (IRATs) were funded by NCI as supplemental grants to existing NCI Cancer Centers. After discussion between the IRATs regarding the need for standardization of clinical and research PET-CT imaging methodology, it became apparent that there were significant differences in data acquisition and processing at the different centers.

Summary: A survey was undertaken to define the range of methodologies at the different centers. 14 institutions, including the 8 original IRATs, were surveyed. The major areas of variation were: FDG dose (7-20 mCi), uptake time (45-90 min), sedation (never to frequently), handling of diabetic patients, imaging time (2-7 min/ bed position), and a wide variation in acquisition, processing, display and PACS software. This wide variation in technique does not seem to affect the utility of FDG PET imaging at the various institutions, however it means it is impossible to utilize their retrospective data in any multi-center analysis of efficacy. It also impedes the ability of the various sites to participate in prospective clinical trials, since baseline studies may have to be repeated. Another significant problem with this wide variation is that sensitivities and specificities in a specific clinical setting, e.g. staging lung cancer, will be different at each institution. Quantitative thresholds, such as SUV, will also be different. This is one reason that the literature in FDG PET imaging is often regarded as inadequate in the eyes of health technology assessment experts. This suggests there is a need to define a guideline for oncologic imaging with FDG PET/CT that is tightly defined and has a minimum variation in key parameters.