PET imaging of sterile inflammation with a 18F-labeled bis(zinc(II)-dipicolylamine) complex

Small-molecular probe 18F-labeled bis(zinc(II)-dipicolylamine) complex (18F-FB-DPAZn2) was evaluated for PET imaging of sterile inflammation. In comparison with 18F-2-deoxy-β-d-glucose (18F-FDG), 18F-radiolabeled Annexin V (18F-FB-Annexin V) showed rapid clearance of radioactivity from the kidney and low uptake in most tissues. Both the lower radioactivity accumulation in brain and heart and the higher uptakes in the lung, liver, and intestine were observed for the biodistribution of 18F-FB-DPAZn2. In PET imaging, 18F-FDG showed significantly higher tumor and inflammation uptake than did of 18F-FB-DPAZn2 and 18F-FB-Annexin V in the S-180 fibrosarcoma mouse model and sterile inflammation mouse model. Both 18F-FB-DPAZn2 and 18F-FB-Annexin V performed the specifically localization in inflammation, and the ratios of inflammatory lesion-to-muscle and tumor-to-muscle were 1.83 ± 0.20 and 0.90 ± 0.12 (P < 0.05) for 18F-FB-DPAZn2, and 1.51 ± 0.14 and 1.21 ± 0.12 (P > 0.05) for 18F-FB-Annexin V, respectively. Terminal deoxynucleotide end-labeling (TUNEL) assays performed on the dissected tissues showed the significantly more TUNEL-positive nuclei in the inflammatory muscle than in tumor and normal muscle, and these TUNEL results correlated with the uptake of 18F-FB-DPAZn2 in dissected tissues. Biodistribution and PET imaging studies showed that the 18F-FB-DPAZn2 is suitable for imaging sterile inflammation in vivo and is capable of the differentiating tumor from inflammation.