68Ga-Pentixafor PET/CT Imaging of Chemokine Receptor CXCR4 in Chronic Infection of the Bone: First Insights

Because of its role in infection and inflammatory processes, the chemokine receptor CXCR4 might be a potent target in imaging of infectious and inflammatory diseases. The aim of this pilot study was to determine whether the CXCR4 ligand Ga-68-pentixafor is suitable for imaging chronic infection of the bone. Methods: The study comprised 14 patients with suspected infection of the skeleton who underwent Ga-68-pentixafor PET/CT between April 2015 and February 2017 in our facility. Ga-68-pentixafor PET/CT results were retrospectively evaluated against a histologic, bacteriologic, and clinical standard. The results were also compared with available bone scintigraphy, white blood cell scintigraphy, and F-18-FDG PET/CT results. Results: Ga-68-pentixafor PET/CT was positive in 9 of 14 patients. Diagnoses included osteitis or osteomyelitis of peripheral bone, osteomyelitis of the maxilla, and infected endoprostheses. Target-to-background ratios were 5.1-15 (mean, 8.7). Eight of 9 cases were true-positive as confirmed by pathology, bacteriology, or clinical observation. All negative cases were confirmed as true-negative by other imaging modalities and follow-up. Conclusion: Imaging of CXCR4 expression with Ga-68-pentixafor PET/CT appears suitable for diagnosing chronic infection of the skeleton. The findings of this study reveal a possible diagnostic gain in suspected chronic infections that are difficult to diagnose by other imaging modalities.