68Ga-Pentixafor PET/CT for Imaging of Chemokine Receptor 4 Expression in Waldenstrom Macroglobulinemia/Lymphoplasmacytic Lymphoma: Comparison to 18F-FDG PET/CT

F-18-FDG PET/CT has some limitations in the evaluation of Waldenstrom macroglobulinemia/lymphoplasmacytic lymphoma (WM/LPL), an indolent B-cell lymphoma that primarily involves the bone marrow. Because there is a high level of chemokine receptor 4 expression in the B cells of WM/LPL patients, we performed a prospective cohort study to evaluate the performance of Ga-68-pentixafor, which targets chemokine receptor 4 in WM/LPL, and to compare it with the performance of F-18-FDG. Methods: Seventeen patients with WM/LPL were recruited. All patients underwent both Ga-68-pentixafor PET/CT and F-18-FDG PET/CT. A positive PET/CT result was defined as the presence of focal lesions with positive PET results or diffuse bone marrow patterns (uptake. liver). The rates of positive results for PET/CT scans of bone marrow, lymph nodes, and other extramedullary involvement were statistically compared. Results: Ga-68-pentixafor PET/CT had a higher rate of positive results than F-18-FDG PET/CT (100% vs. 58.8%; P = 0.023) in the recruited WM/LPL patients. The sensitivities of 68Ga-pentixafor PET/CT and F-18-FDG PET/CT for detecting bone marrow involvement were 94.1% and 58.8%, respectively (P = 0.077). In terms of detecting lymph node involvement, Ga-68-pentixafor PET/CT had a significantly higher rate of positive results than F-18-FDG PET/CT (76.5% vs. 11.8%; P = 0.003). In addition, Ga-68-pentixafor detected more paramedullary and central nervous system involvement than F-18-FDG. Conclusion: Ga-68-pentixafor might be a promising imaging agent for the assessment of WM/LPL.