Evaluation of [89Zr]-Oxalate as a PET Tracer in Inflammation, Tumor, and Rheumatoid Arthritis Models

Abstract

To obtain an additional pharmacological agent for the diagnosis of inflammation, we investigated the medical use of ⁸⁹Zr-oxalate as a positron emission tomography (PET) probe for the in vivo imaging of inflammation and compared its efficacy to that of 2-deoxy-2-[¹⁸F]fluoro-d-glucose ([¹⁸F]FDG) and sodium [¹⁸F]fluoride. ⁸⁹Zr-oxalate exhibited observable higher uptake in a macrophage cell line than in tumor cells. The inflammatory lesions and tumors were clearly visualized by PET imaging and autoradiography using ⁸⁹Zr-oxalate. Compared to [¹⁸F]FDG and sodium [¹⁸F]fluoride, ⁸⁹Zr-oxalate demonstrated a high selectivity index to the tumor at an early time point after injection and to inflammation at a delayed time point after injection (24 h). Through histological examination, large numbers of macrophages and neutrophils were observed in the tumor lesions with the highest ⁸⁹Zr-oxalate uptake. In a rheumatoid arthritis (RA) mouse model, ⁸⁹Zr-oxalate demonstrated a high level of accumulation in inflammatory lesions. ⁸⁹Zr-oxalate is a new strategic tool for tumor imaging and inflammatory processes.