Comparative Evaluation of FET and FDG for Differentiating Lung Carcinoma from Inflammation in Mice

Background: Clinical FDG/PET (2-deoxy-2- 18 F-fluoro-D-glucose/positron emission tomography) studies encounter difficulties in detecting early stage lung cancers. The aim of this study was to evaluate the ability of O-2- 18 F-fluoroethyl-L-tyrosine (FET) and FDG to differentiate between inflammation and lung carcinoma in mice. Materials and Methods: Sixty-four C57BL/6 mice were inoculated with 2x10 6 LLC1 lung carcinoma cells in the right hind flank on day 0 and were then injected with 0.1 mL turpentine in the left thigh muscle on day 3. The progress of inflammation and tumor in mice was longitudinally monitored by FDG/microPET. The biodistribution study, pharmacokinetic evaluation and whole-body autoradiography of FET and FDG were performed on day 8 after tumor inoculation. Results: The FDG uptakes in tumor and inflammatory lesions were 4.42-fold and 3.53-fold (n=4) higher, respectively, than that in muscle at 90 min post-injection and the tumor-to-inflammation ratio was 1.25. For FET/microPET, the tumor uptake was 2.07-fold and 2.07-fold (n=4) higher than those in muscle and inflammatory lesions at 90 min post-injection, respectively. The distribution half-life (t 1/2,α ) and the elimination half-life (t 1/2,β ) of FET were 39 min and 205 min, respectively, in mice. Conclusion: FDG delineated both tumor and inflammation, while FET accumulated in tumor to a significantly higher extent. Our results demonstrated the potential of FET to distinguish epidermoid lung carcinoma from inflammatory lesions in mice.