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

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.