Comparison of MRI, [18F]FDG-PET/CT, and [18F]FDG-PET/MRI for Initial Staging of Multiple Myeloma

Purpose: This systematic review and meta-analysis compared the diagnostic performance of MRI, [ 18 F]FDG-PET/CT, and [ 18 F]FDG-PET/MRI in detecting focal bone lesions and bone marrow infiltration in the initial staging of patients with multiple myeloma (MM) who underwent both MRI and [ 18 F]FDG-PET/CT or [ 18 F]FDG-PET/MRI studies. Patients and Methods: A systematic literature search was conducted across PubMed, Embase, and Cochrane databases, including studies comparing the performance of MRI (WB-MRI or spine/pelvis MRI), [ 18 F]FDG-PET/CT, and/or [ 18 F]FDG-PET/MRI in the same patients for MM initial staging. Pooled sensitivities and concordance between imaging modalities were analyzed using R (package META-R). Heterogeneity and bias were assessed with the QUADAS-C tool. Results: Twenty studies (published between 2007 and 2025) using the international MM diagnostic criteria as a reference standard met the inclusion criteria. Of these, 13 (n=742) compared per-patient sensitivity of [ 18 F]FDG-PET/CT and MRI, and 4 (n=224) compared MRI and [ 18 F]FDG-PET/MRI. Pooled sensitivities were 0.807 (95% CI: 0.74–0.86) for [ 18 F]FDG-PET/CT (with significant heterogeneity) versus 0.914 (95% CI: 0.88–0.94) for MRI (0.906 for spine/pelvis MRI and 0.920 for WB-MRI) ( P <0.001 for meta-regression analysis). Using contingency tables, 83% (599/721) of included patients had concordant [ 18 F]FDG-PET/CT and MRI results, while 14% (101/721) patients had negative [ 18 F]FDG-PET/CT and positive MRI with significant differences between the 2 techniques for the paired sample analysis ( P <0.001). The pooled sensitivity of the 4 studies including [ 18 F]FDG-PET/MRI was 0.944 (95% CI: 0.88–0.98). Consensus definitions for specificity in MM imaging should be standardized across studies. Conclusions: This systematic review and comparative meta-analysis demonstrates superior sensitivity of WB-MRI compared with [ 18 F]FDG-PET/CT for initial staging of MM patients. Future international guidelines might prioritize MRI and [ 18 F]FDG-PET/MRI for staging of MM patients. Registration PROSPERO CRD42024564937.