ABSTRACT
OBJECTIVES: Longitudinal assessment of changes in apparent diffusion coefficient (ADC)-values in multiple myeloma (MM) patients and their potential role for classifying disease activity. METHODS: Retrospective analysis of whole-body-MRI data in 73 stage III MM patients undergoing systemic treatment. Bone marrow involvement was evaluated using a standardized unenhanced 4-sequences whole-body-MRI protocol. We measured ADC-values in focal lesions (FL) and diffusely involved bone marrow (DIBM) areas. Response to treatment was based on the course of hematologic parameters. The time points of MRI-examinations were baseline, 1st (mean, 3 months), 2nd (mean, 10 months), and 3rd (mean, 18 months) follow up (FU). RESULTS: Mean IgG and IgA serum values at baseline were 2.1â¯mg/dl and 1.8â¯mg/dl, respectively. Patients were classified into responders (nâ¯=â¯59) and non-responders (nâ¯=â¯34). Some patients were re-enrolled for new treatment regimens as they became therapy-refractory. Patterns of medullary involvement were focal (nâ¯=â¯44), diffuse (nâ¯=â¯61) and mixed (nâ¯=â¯30). In FL, a subgroup of myeloma patients undergoing short-term 1st FU experienced a significant increase in ADC in responders (pâ¯=â¯0.001), but not in non-responders (pâ¯=â¯0.9). In the further course of the study, ADC levels decreased continuously in responders (pâ¯=â¯0.02) and increased slightly in non-responders (pâ¯=â¯0.8). In patients with DIBM, ADC values decreased in the responders (pâ¯<â¯0.001) and in the non-responders (pâ¯=â¯0.78). An ADC cut-off value of 0.5-0.6â¯×â¯10-3 â¯mm2/s for diagnosing inactive disease at follow-up proved unreliable. CONCLUSIONS: In myeloma-patients with lower tumor burden, the longitudinal course of ADC-values is predictable only for FL whereas for DIBM ADC-changes considerably overlap between responders and non-responders and are not indicative for assessment of the disease activity.
