Different extramedullary disease shown in chemokine receptor 4 targeted PET/CT with [ 68 Ga]Ga-pentixafor in patients with Waldenström macroglobulinemia and smoldering disease.

Introduction: It is important to distinguish Waldenström macroglobulinemia from smoldering Waldenström macroglobulinemia (sWM), because only patients with Waldenström macroglobulinemia require treatment, however the distinction can be clinically complex. The aim of this study is to investigate whether [ 68 Ga]Ga-pentixafor PET/CT shows different characteristics in sWM and Waldenström macroglobulinemia patients and therefore can help to differentiate Waldenström macroglobulinemia and sWM.

Results: Thirty-seven patients with newly diagnosed Waldenström macroglobulinemia and 11 sWM patients were analyzed [35 men and 13 women; 64.3 ± 10.7 (range, 29-87) years old]. The SUV max of bone marrow disease, lymph nodes, and other extramedullary diseases on [ 68 Ga]Ga-pentixafor were significantly higher than those on 2-[ 18 F]FDG PET/CT ( P  < 0.05). On [ 68 Ga]Ga-pentixafor PET/CT, patients with Waldenström macroglobulinemia had more lymph node regions involved, significantly higher incidence of involvement in more than three lymph node regions, larger nodal disease, and higher incidence of other extramedullary disease when compared with sWM patients ( P  < 0.05). Waldenström macroglobulinemia patients showed significantly higher total lesions uptake, total lesion volume, and SUV max of extramedullary disease than sWM patients did ( P  < 0.05). None of the visual or semiquantitative indexes in 2-[ 18 F]FDG PET/CT showed significant difference between Waldenström macroglobulinemia and sWM patients.

Conclusion: [ 68 Ga]Ga-pentixafor PET/CT had better diagnostic performance than 2-[ 18 F]FDG PET/CT in Waldenström macroglobulinemia. Patients with Waldenström macroglobulinemia presented with more extensive extramedullary disease shown in [ 68 Ga]Ga-pentixafor PET/CT than sWM patients did.