Molecular imaging in Multiple Myeloma

Multiple myeloma (MM) stands as the predominant primary malignancy of the bone, characterized by plasma cell dyscrasia and resultant organ damage. The assessment of disease involvement relies on a combination of clinical, laboratory and imaging findings. Among various imaging modalities, F18 FDG PET/CT is commonly recommended, although its sensitivity may be limited in specific case cohorts. Consequently, the utilization of IMPeTUs criteria has been shown to enhance examination sensitivity. Nonetheless, ongoing exploration of molecular agents seeks alternatives with heightened sensitivity in disease assessment, notably choline-based PET agents emerging as prominent candidates within molecular imaging methodologies. Preliminary investigations with F18 Fluorocholine (FCH) PET/CT in limited study cohorts have suggested superior diagnostic performance compared to FDG. Our objective is to delineate the diagnostic efficacy of molecular imaging in MM patients, refine imaging parameters, correlate methods with clinical and laboratory findings and contribute novel insights to radiopharmaceutical literature, particularly regarding agents like FCH anticipated for widespread accessibility in the future. Hence, our study entails a comparative analysis of the diagnostic performances of FDG and FCH examinations according to IMPeTUs criteria. Furthermore, we investigate the associations between both imaging modalities and clinical as well as laboratory parameters. For skeletal assessment, FCH demonstrated higher sensitivity in both case-based and region-based analyses compared to FDG, exhibiting superior performance. Evaluation of extramedullary disease (lymph nodes and soft tissue; which has demonstrated prognostic significance), revealed equivalent performance for both methods. While IMPeTUs recommendations proved adaptable to FCH, Deauville 3 yielded poor predictive value for assessing widespread bone marrow infiltration in both tests. The study delved into imaging and clinical correlation, revealing a stronger association between tumor burden and laboratory-clinical findings with FCH compared to FDG. To refine the methodology, FCH imaging was conducted at two time points and analysis indicated no significant disparity between images obtained at the tenth and sixtieth minutes, suggesting that imaging at the tenth minute may suffice. Moreover, considering the consistent observation of widespread disease in patients with distal lower extremity lesions, it was concluded that inclusion of the distal lower extremity in imaging protocols for every patient is unnecessary as a standard practice. Conclusively, FCH emerges as a viable option in MM, particularly when FDG fails to demonstrate metabolic activity or yields clinically inconclusive results and notably excels in detecting minimal residual disease. Keywords: Multiple myeloma, F18 FCH, F18 FDG, molecular imaging