The presence and number of bone lesions detected by whole body magnetic resonance imaging (MRI) can be used to determine the likelihood of progression from smoldering (asymptomatic) multiple myeloma to active (symptomatic) myeloma, according to a study published in the Journal of Clinical Oncology.

Patients with more than one bone lesion progressed sooner than those with one or zero.

Currently, MRI, a technique commonly used to visualize internal structure of the body, is one of the most sensitive techniques for detecting bone lesions and changes in bone marrow in multiple myeloma patients. Spinal MRI is commonly recommended for detecting bone lesions in patients with asymptomatic blood disorders, such as monoclonal gammopathy of undetermined significance and smoldering myeloma.

However, spinal MRI misses any bone lesions that occur away from the spine and pelvis, which can amount to 50 percent of bone lesions in myeloma patients. As a result, patients who are at high-risk of progressing to active myeloma may not be identified.

This study included 149 patients diagnosed with smoldering myeloma. Only one patient showed signs of bone disease, and none of the patients received treatment for smoldering myeloma. Follow-up evaluations occurred every 3 to 6 months, and the median time of follow-up for the whole group was 23.7 months.

Bone lesions were found in 28 percent of the study participants, with the number of lesions ranging from one to more than 20. Eight percent of patients had lesions located only on the spine, 13 percent had lesions only away from the spine, and 7 percent had lesions in both areas.

After analyzing how long it took participants to progress from smoldering to symptomatic myeloma, the researchers concluded that patients with more than one bone lesion progressed significantly faster than the rest. Among these high-risk patients, 39 percent had lesions away from their spine only. Such lesions would not have been detected without whole body MRI, and the skeletal involvement of myeloma would have been overlooked.

MRI can also detect when cancerous cells slowly replace normal marrow, known as diffuse bone marrow infiltration. This was detected in 40 percent of study participants, regardless of the presence of bone lesions. Bone marrow infiltration was also found to be adversely associated with progression to symptomatic myeloma; however, it can be difficult to detect.

Additionally, the researchers statistically evaluated several standard factors for assessing the probability of progression to symptomatic myeloma, such as concentration of M protein, plasma cells in the bone marrow, and the presence or absence of certain immunoglobulins (antibodies).

The researchers determined that the MRI-derived risk-factors were the only ones statistically correlated with progression to symptomatic myeloma. A cutoff of more than one bone lesion detected by whole body MRI was the most effective at differentiating between high- and low-risk progression to symptomatic myeloma.

Based on this study, the study authors recommend whole body MRI to determine a patient’s risk group. However, it was not determined whether smoldering myeloma patients who have bone lesions would benefit from treatment.

For more information, please see the research article in the Journal of Clinical Oncology (abstract).