Value of MRI in Smoldering Myeloma Stressed by the International Myeloma Working Group
All patients with smoldering or asymptomatic multiple myeloma should undergo whole-body magnetic resonance imaging (MRI), or pelvic and spinal MRI if whole body is unavailable, according to recommendations from the International Myeloma Working Group (IMWG). The presence of >1 focal lesions >5 mm should be considered diagnostic for symptomatic myeloma requiring therapy.
MRI is not recommended as part of the routine workup in patients with monoclonal gammopathy of undetermined significance (MGUS), unless specific clinical characteristics increase the level of suspicion, according to new recommendations from the IMWG (Dimopoulos MA, et al. J Clin Oncol. 2015;33:657-664).
A New Gold Standard
Characterizing MRI as the “gold standard” for detecting bone marrow involvement in myeloma, the new recommendations update the previous suggestion from the IMWG that whole-body x-ray should remain the standard for the evaluation of myeloma-related bone disease.
“In its previous recommendations, the IMWG supported the use of MRI in the absence of osteolytic lesions on whole-body x-ray,” stated Meletios A. Dimopoulos, MD, Chair of Clinical Therapeutics, National and Kapodistrian University of Athens School of Medicine, Greece, and colleagues. However, the group did not suggest the use of MRI for symptomatic myeloma.
Therefore, a patient with focal lesions on MRI but with no lytic lesions on whole-body x-ray and with no other criteria of hypercalcemia, renal failure, anemia, and bone disease (CRAB) is “considered to have smoldering or asymptomatic myeloma, and follow-up with no treatment is recommended,” the team noted.
Now new data highlight the value of MRI in this setting, suggesting that the current practice should be changed accordingly. The panel analyzed evidence for various types of MRI, and the role of MRI in symptomatic, as well as asymptomatic myeloma, smoldering myeloma, and MGUS.
Updated MRI Recommendations
For symptomatic myeloma, the panel affirmed that MRI is the gold standard approach to detecting bone marrow involvement in patients with multiple myeloma, but emphasized that MRI only detects bone marrow involvement, not bone destruction in the disease.
Although whole-body MRI is the preferred imaging technique, MRI of the spine and pelvis can detect approximately 90% of focal lesions in myeloma, making it an acceptable alternative when whole-body MRI is not available.
MRI is the “procedure of choice” for evaluating painful skeletal lesions and for detecting spinal cord compression. MRI is particularly useful for evaluating collapsed vertebrae when myeloma is not active.
The panel concluded that the presence of >7 focal lesions on MRI in combination with a diffuse pattern correlate with inferior survival. Whether these patients require a different approach to treatment is a question that requires a clinical trial to resolve.
As for the question of following patients for response to therapy, the panel found MRI associated with a high false-positive rate and, in the absence of clinical indications, “is not recommended.”
The evidence showed that:
- MRI reveals abnormal marrow in as many as 50% of patients who have no osteolytic lesions on whole-body x-ray
- MRI is useful for the evaluation of symptomatic patients who are at high risk for disease
- Identifying patients with multiple myeloma who are at risk for progression from asymptomatic to symptomatic disease remains a major unresolved issue
- MRI improved the identification of such patients better than the CRAB criteria. Finally, the evidence for the use of MRI to identify a single-bone plasmacytoma (SBP) shows that “MRI should be part of the staging procedures in patients with SBP to better assess the extent of the local tumor and reveal occult lesions elsewhere,” according to the expert panel. Based on this new analysis, the expert panel now recommends that:
- Patients with >1 unequivocal focal lesion that is >5 mm on MRI be considered symptomatic and require therapy
- Patients with equivocal focal lesions should have a repeated MRI after 3 to 6 months, and evidence of progression should be considered symptomatic disease that is in need of therapy. The data were less compelling for the role of MRI in MGUS. The panel concluded that whole-body MRI “identifies patients with MGUS with focal lesions that possibly reflect infiltration by monoclonal plasma cells in the bone marrow. These patients seem to have increased risk of progression to myeloma.”
In keeping with the evidence, the panel said that “MRI is not recommended as part of the routine workup for patients with MGUS unless there are clinical features that increase suspicion.”