Whole Body MRI (WB-MRI) in patients affected by monoclonal plasma cell disorders

Purpose This PhD research evaluates the impact of multiparametric Whole Body-Magnetic Resonance Imaging (WB-MRI) in myeloma patients, comparing its diagnostic accuracy with 18F-FDG PET-CT and assessing its influence on clinical management. Additionally, it explores quantitative WB-MRI using radiomics. Materials and Methods Within the AccuMRI IRST protocol, 177 patients were enrolled (October 2020–January 2024), with 134 undergoing both WB-MRI and PET-CT within one month. Bone marrow involvement (BMI) detection was eveluated in multiple myeloma (MM) and high-risk smoldering multiple myeloma (HR-SMM). Inter-reader agreement among three radiologists was assessed in 52 patients, and WB-MRI acceptancy was evaluated in 134 patients. Quantitative WB-MRI using radiomics was analyzed in 84 patients (45 MM, 39 HR-SMM), focusing on Apparent Diffusion Coefficient (ADC) and fat fraction (FF) sequences. Six volumes of interest (VOIs) were placed in pelvic bones and spine. Logistic regression with LASSO selection was used for feature analysis. Results WB-MRI showed 100% sensitivity and 97% specificity for BMI detection in MM, outperforming PET-CT (sensitivity 89%, p=0.02). Patients with BMI had higher blood paraprotein levels (p=0.007 in MM, p=0.01 in HR-SMM) and lower hemoglobin (p=0.002 in MM). WB-MRI findings influenced treatment in 97% of cases vs. 61% for PET-CT. Inter-reader agreement was excellent (ICC > 0.9 for FF and ADC, except limbs: ICC=0.78). WB-MRI was preferred by 68.7% of patients, with preference influenced by age (p=0.011). Radiomics models distinguished HR-SMM from MM (AUC=0.80 training, 0.70 test), with RS VOI showing highest accuracy (AUC=0.76). FF and ADC correlated with plasma cell percentage. Conclusion WB-MRI and PET-CT play key roles in evaluating myeloma patients. WB-MRI demonstrated superior sensitivity in detecting BMI and had a greater influence on therapeutic decision-making. MY-RADS criteria ensure reproducibility and radiomics could enhance risk stratification. WB-MRI is a reliable, patient-friendly imaging tool for myeloma.