Comparison of three 18F-labeled carboxylic acids with 18F-FDG of the differentiation tumor from inflammation in model mice

BACKGROUND The aim of this study was to compare the properties and feasibility of the glucose analog, 2-(18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG), three short (18)F-labeled carboxylic acids, (18)F-fluoroacetate ((18)F-FAC), 2-(18)F-fluoropropionic acid ((18)F-FPA) and 4-((18)F)fluorobenzoic acid ((18)F-FBA), for differentiating tumors from inflammation. METHODS Biodistributions of (18)F-FAC, (18)F-FPA and (18)F-FBA were determined on normal Kunming mice, and positron emission tomography (PET) imaging with these tracers were performed on the separate tumor-bearing mice model and inflammation mice model in comparison with (18)F-FDG. RESULTS Biodistribution results showed that (18)F-FAC and (18)F-FPA had similar biodistribution profiles and the slow radioactivity clearance from most tissues excluding the in vivo defluorination of (18)F-FAC, and (18)F-FBA demonstrated a lower uptake and fast clearance in most tissues. PET imaging with (18)F-FDG, (18)F-FAC and (18)F-FPA revealed the high uptake in both tumor and inflammatory lesions. The ratios of tumor-to-inflammation were 1.63 ± 0.28 for (18)F-FDG, 1.20 ± 0.38 for (18)F-FAC, and 1.41 ± 0.33 for (18)F-FPA at 60 min postinjection, respectively. While clear tumor images with high contrast between tumor and inflammation lesion were observed in (18)F-FBA/PET with the highest ratio of tumor-to-inflammation (1.98 ± 0.15). CONCLUSIONS Our data demonstrated (18)F-FBA is a promising PET probe to distinguish tumor from inflammation. But the further modification of (18)F-FBA structure is required to improve its pharmacokinetics.