Clinical utility and reproducibility of standardized PET-CT criteria in multiple myeloma: real-world implementation and prognostic relevance

Abstract Background In multiple myeloma (MM), bone lesions can be assessed using whole-body X-ray (WBXR), computed tomography (CT), magnetic resonance (MR) or positron emission tomography (PET). The Italian Myeloma Criteria for PET Use (IMPeTUs) criteria for F-18 fluorodeoxyglucose positron emission tomography–computed tomography (F-18 FDG PET/CT) evaluation were introduced in 2016 and validated in 2018, but real-word reproducibility and clinical correlations remain unexplored. This study fills the critical gap between trial-validated IMPeTUs criteria and routine clinical practice, validating reproducibility and establishing prognostic correlations for risk-stratified therapy decisions. Methodology Non-randomized single-center cohort (n = 21 newly diagnosed MM) underwent PET-CT evaluation pre-induction (PET-0) and two weeks (PET-1) after completion of induction chemotherapy. Two blinded nuclear medicine experts (SS and PS) independently scored using IMPeTUs criteria. Inter-observer agreement (Cohen’s k) and clinical-imaging correlations (Pearson r) were calculated. Results Inter-observer agreement: Substantial agreement found for bone marrow (BM) Deauville score (Kappa—0.790; 0.781) and almost perfect agreement for focal lesions (Kappa—0.931; 0.821), lytic lesions (Kappa—0.923; 0.933), and fractures (Kappa—1.0; 1.0). For paramedullary lesions, both observers had a moderate agreement (0.462) on PET-0 and negative agreement (− 0.05) on PET-1 whereas for the extramedullary lesions, there was a good agreement at PET-0 (0.814) and moderate agreement (0.462) at PET-1. Conclusion IMPeTUs criteria achieve robust reproducibility in routine practice with prognostic correlations supporting real-world therapy management.