18F-PBR06 PET/CT imaging of inflammation and differentiation of lung cancer in mice

The present study explored the 18-kDa translocator protein radioligand 18F-PBR06 as a PET imaging biomarker for diagnosis of inflammation and compared it with 18F-FDG for differentiation of inflammation and lung tumors in animals. 18F-PBR06 was synthesized with an average decay-corrected radiochemical yield of 30–40% (end of synthesis, EOS), and the radiochemical purity was greater than 99%. The inflammation-to-blood ratio of 18F-PBR06 (3.53 ± 0.26) was higher than the tumor-to-blood ratio (1.77 ± 0.35) (P < 0.001). The inflammation-to-muscle ratio of 18F-PBR06 (2.33 ± 0.64) was also higher than the tumor-to-muscle ratio (1.45 ± 0.14) (P = 0.036). Micro-PET/CT images showed high uptake of 18F-FDG in both inflamed muscles and lung tumor tissues. However, 18F-PBR06 uptake in inflamed muscles remained higher than that in the lung tumor tissues, following 90 min of dynamic Micro-PET/CT imaging. Further, macrophages in the inflammatory regions showed a higher fluorescence signal than in lung tumor tissues. Results of the study confirmed that 18F-PBR06 PET/CT imaging allowed for diagnosis of inflammation. Moreover, 18F-PBR06 uptake in the inflammatory regions was significantly higher than in lung tumor tissues, suggesting that 18F-PBR06 PET/CT imaging has potential to differentiate between peripheral lung cancer and inflammation nodules.