Impacts of time interval on 18F-FDG uptake for PET/CT in normal organs: A systematic review

BACKGROUND: To perform a systematic review of the effect of time interval on 2-deoxy-2-[18F] fluoro-D-glucose (18F-FDG) uptake in normal organs. METHODS: PubMed, EMBASE, Ovid, and Cochrane databases were searched to identity all potential eligible literature. The study characteristics and relevant data were extracted and analyzed. We adopted the effect size (ES) and the coefficient of determination (R(2)) to best measure the magnitude of the relation between time interval and 18F-FDG uptake in normal organs. RESULTS: Seven articles and 860 participants were included. The time interval on liver and mediastinal blood pool were relatively medium (R(2)=0.01–0.03, ES = –0.57 and –0.60) but noticeable (R(2) = 0.06, ES = –0.68 and –0.39), respectively. The uptake of 18F-FDG on cerebellum, spleen, bone marrow, muscle, bowel, and adipose remains to be verified as the rare studies. In addition, other factors such as body mass index and blood glucose level appeared to be important which also affect 18F-FDG uptake in normal organs. CONCLUSION: The impact of time interval on SUVs in liver and mediastinal blood pool were relatively medium but clinically noticeable. More studies need to be done to solve the relation between the SUVs of other organs and time interval.