Comparison of (68)Ga-DOTA-Siglec-9 and (18)F-Fluorodeoxyribose-Siglec-9: Inflammation Imaging and Radiation Dosimetry

Sialic acid-binding immunoglobulin-like lectin 9 (Siglec-9) is a ligand of inflammation-inducible vascular adhesion protein-1 (VAP-1). We compared (68)Ga-DOTA- and (18)F-fluorodeoxyribose- (FDR-) labeled Siglec-9 motif peptides for PET imaging of inflammation. Methods. Firstly, we examined (68)Ga-DOTA-Siglec-9 and (18)F-FDR-Siglec-9 in rats with skin/muscle inflammation. We then studied (18)F-FDR-Siglec-9 for the detection of inflamed atherosclerotic plaques in mice and compared it with previous (68)Ga-DOTA-Siglec-9 results. Lastly, we estimated human radiation dosimetry from the rat data. Results. In rats, (68)Ga-DOTA-Siglec-9 (SUV, 0.88 ± 0.087) and (18)F-FDR-Siglec-9 (SUV, 0.77 ± 0.22) showed comparable (P = 0.29) imaging of inflammation. In atherosclerotic mice, (18)F-FDR-Siglec-9 detected inflamed plaques with a target-to-background ratio (1.6 ± 0.078) similar to previously tested (68)Ga-DOTA-Siglec-9 (P = 0.35). Human effective dose estimates for (68)Ga-DOTA-Siglec-9 and (18)F-FDR-Siglec-9 were 0.024 and 0.022 mSv/MBq, respectively. Conclusion. Both tracers are suitable for PET imaging of inflammation. The easier production and lower cost of (68)Ga-DOTA-Siglec-9 present advantages over (18)F-FDR-Siglec-9, indicating it as a primary choice for clinical studies.