[Contribution of whole-body magnetic resonance in the diagnostics of monoclonal gammopathy of undetermined significance, multiple myeloma, and the assessment of Durie-Salmon Plus staging system].

BACKGROUND

The aim of the study was to assess the contribution of the whole body MRI (WB-MRI) in the diagnostics of monoclonal gammopathy of undetermined significance (MGUS) and initial, asymptomatic form of multiple myeloma (MM), as well as the evaluation of practical usefulness of the Durie-Salmon Plus staging system (D-S Plus).

MATERIALS AND METHODS

The analyzed 86-patient cohort consisted of 28 patients with MGUS and 54 patients with newly diagnosed multiple myeloma and 4 patients with solitary plasmocytoma (SP). WB-MRI was evaluated using Magnetom Avanto 1.5 T with the use of virtual whole body coil with sequential acquisition on 7 levels and 2 sequentions--T2 STIR and T1. Based on the number of lesions and the degree of diffuse involvement we assessed the D-S Plus stage, and compared it to the results of standard staging systems according to Durie Salmon (D-S) and International Staging System (ISS). Statistical estimation was done using the Cohen kappa test and McNemara-Bowker test at p < 0.05.

RESULTS

In the group of 28 individuals with MGUS, there were 17 (61%) patients fulfilling the IMWG criteria and/orWB-MRI criteria of incipient MM. In 4/17 (23%) patients we described a more advanced stage when comparing D-S Plus to D-S. Nine out of fourteen (64%) patients with MGUS transforming into MM with negative radiological assessment had positive findings on WB-MRI. The character of WB-MRI findings lead in 9/17 (53%) of the patients to the initiation of induction treatment. Stratification according to D-S Plus divided the 54 newly diagnosed patients with MM into stage 1 (16.7%), stage 2 (33.3%) and stage 3 (50%). In 22% there was a shift into a higher stage using DS-Plus in comparison with D-S, in 9% of the patients the shift lead to downstaging. When comparing the results of ISS vs D-S Plus we found that the system based on WB-MRI showed in 41% of the patients higher stage and only in 9% of the patients lower stage. In 13% of MM patients we described extramedulary masses of the tumor, especially in paraspinal region. In 1 of the 4 SP patients the WB-MRI changed the diagnosis into multifocal plasmocytoma.

CONCLUSION

WB-MRI is a very contributive imaging method with substantially higher resolution than conventional radiography. It is able to evaluate the grade and the extent of myeloma bone disease. It improves the diagnostic approach in the differentiation of stable MGUS from the phase of malignant transformation into MM. The D-S Plus system proved to be contributive and is competent to become a routine part of diagnostic and stratification algorithms in MGUS and MM.