O-(2-[¹⁸F]fluoroethyl)-L-tyrosine (¹⁸F-FET) uptake in mouse thymoma cells, and its biodistribution in mice and human volunteers

Purpose: To evaluate O-(2-[¹⁸F]fluoroethyl)-l-tyrosine (¹⁸F-FET) uptake in mouse malignant thymoma (EL4), and its biodistribution in mice and humans.

Material and Methods: First, ¹⁸F-FET uptake in EL4 cells was examined in an in vitro study. Second, the kinetics of ¹⁸F-FET uptake and its biodistribution were examined in mice after subcutaneous injection of EL4 cells and complete Freund's adjuvant. Finally, the kinetics of ¹⁸F-FET uptake and its biodistribution in healthy human volunteers were examined.

Results: In an in vitro study, ¹⁸F-FET was extensively incorporated in EL4 cells. In an animal study, ¹⁸F-FET accumulation in normal organs peaked within 30 min postinjection. The mean ratios of ¹⁸F-FET uptake in tumors and in inflammatory lesions to that in muscle tissue at 60 min postadministration were 2.18 (range 2.00-2.29) and 1.04 (range 0.95-1.14), respectively. In a human study, static images were taken 60 min after ¹⁸F-FET administration. Mean standardized uptake values (SUVs) of the liver (1.52, range 1.38-1.71) and kidneys (1.90, range 1.74-2.24) were nearly equal or slightly higher than that of muscle tissue (1.19, range 0.99-1.33).

Conclusion: This study demonstrates that ¹⁸F-FET accumulation in thymoma is significantly higher than in normal organs. ¹⁸F-FET could be a useful tracer for tumor imaging.