18F-FDG PET/CT for the detection of residual or recurrent disease in myeloma patients after allogeneic stem cell transplantation

Objectives There is an increasing need for accurate evaluation of treatment response in multiple myeloma. Sytems serving that purpose are mainly based on the assessment of certain hematologic parameters but their use is accompanied by many pitfalls. Additional morphologic imaging is of limited usefulness as osteolytic bone lesions may persist for several years even if the patients are in complete remission. The aim of this study was to evaluate the ability of 18F-FDG PET/CT to detect active myeloma lesions presenting residual or recurrent disease in patients after allogeneic stem cell transplantation.

Methods 56 treated myeloma patients (34 male, median age 51 years) underwent whole-body 18F-FDG PET/CT after allogeneic stem cell transplantation. Number and size of lesions detected by 18F-FDG PET/CT were compared with remission status as determined by hematologic parameters.

Results 18F-FDG PET/CT was positive in 22 patients showing either focal or diffuse disease. 12 of these patients had abnormal laboratory results. F-18-FDG PET/CT was negative in 10 patients with abnormal serologic findings. 24 patients without abnormal serologic findings were concordantly found to have no evidence of residual or recurrent disease on 18F-FDG PET/CT.

Conclusions 18F-FDG PET/CT appears to provide relevant additional information in a substantial number of patients after allogeneic stem cell transplantation. Correct identification of sites and extent of involvement may have significant implications for appropriate treatment of recurrent myeloma.