PET/CT Imaging for Therapy Assessment in Multiple Myeloma Including MRD

Background/Objectives: Multiple myeloma (MM) is a complex hematologic malignancy characterized by abnormal plasma cell proliferation in the bone marrow. [¹⁸F]FDG PET/CT has emerged as a key imaging modality, demonstrating high sensitivity and specificity for the detection of metabolically active disease compared with conventional imaging techniques. This review examines the role of PET/CT imaging in evaluating therapeutic response in symptomatic myeloma, including minimal residual disease (MRD) assessment. Methods: We surveyed the literature published between 2014 and 2024 across PubMed, Scopus, Web of Science, and the Cochrane Library for peer-reviewed articles evaluating PET imaging in the assessment of treatment response in multiple myeloma. Results: [¹⁸F]FDG PET/CT provides a whole-body assessment of disease burden, extramedullary involvement detection, and early metabolic response evaluation. Standardized response assessment criteria (Deauville, IMPeTUs, IMWG) have enhanced the reproducibility and accuracy of treatment monitoring. Semiquantitative parameters including SUVmax and metabolic tumor volume (MTV) provide useful prognostic information with PET negativity correlating with improved progression-free and overall survival. The integration of PET/CT with bone marrow assessment techniques (next-generation flow cytometry and sequencing) optimizes MRD evaluation and patient stratification. Conclusions: PET/CT represents a valuable imaging tool for improving therapeutic decision making and risk stratification in MM management. Emerging radiotracers beyond FDG, including [¹¹C]choline, [¹¹C]methionine, and targeted agents like [⁶⁸Ga]pentixafor and CD38-targeted immunoPET tracers, hold promise for enhanced diagnostic capabilities in specific clinical contexts.