Bone marrow 18F-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography cannot replace bone marrow biopsy in diffuse large B-cell lymphoma

This study aimed to investigate whether visual and quantitative (18) F-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (FDG-PET/CT)-based bone marrow assessment can replace blind bone marrow biopsy (BMB) in newly diagnosed diffuse large B-cell lymphoma (DLBCL). This retrospective study included 78 patients with newly diagnosed DLBCL who had undergone both FDG-PET/CT and BMB. FDG-PET/CT images were visually evaluated for bone marrow involvement. Patient-based sensitivity of visual FDG-PET/CT assessment was calculated using BMB as the reference standard. Metabolically active volume, maximum standardized uptake value, 3D partial volume corrected mean standardized uptake value, and 3D partial volume corrected mean metabolic volume product (cMVPmean ) of FDG-avid bone marrow lesions were measured. Cox regression analysis was used to determine the influence of (potential) prognostic factors (BMB status, visual [dichotomous] FDG-PET/CT bone marrow status, metabolically active volume, maximum standardized uptake value, 3D partial volume corrected mean standardized uptake value, 3D partial volume corrected mean metabolic volume product, and International Prognostic Index score) on progression-free survival and overall survival. FDG-PET/CT detected bone marrow involvement in 34 (43.6%) cases and BMB in 16 (20.5%) of 78 cases, of whom 11 were also detected by FDG-PET/CT, resulting in a patient-based sensitivity of 68.8% (95% confidence interval = 44.2%-86.1%) for FDG-PET/CT. In the multivariate Cox proportional hazards model, only BMB status was an independent predictive factor of progression-free survival (P = 0.016) and overall survival (P = 0.004). In conclusion, FDG-PET/CT misses bone marrow involvement that has been detected by BMB in a non-negligible proportion of patients. Furthermore, both visual and quantitative FDG-PET/CT-based bone marrow assessments are prognostically inferior to BMB. Therefore, FDG-PET/CT cannot replace BMB in newly diagnosed DLBCL.