Magnetic resonance imaging findings in multiple myeloma: description and predictive value

Abstract Objective. Multiple myeloma is a malignant plasma cell dyscrasia that arises in the bone marrow and produces osteolytic lesions. Radiological osteolysis is among the criteria in the Durie and Salmon classification scheme, which is the most widely used classification system for evaluating the tumor burden and, consequently, the prognosis in multiple myeloma. However, magnetic resonance imaging (MRI) is the best investigation for visualizing the bone marrow, where the disease starts. MRI has gained acceptance as the investigation of choice for diagnosing spinal cord compression, particularly in myeloma patients. We sought to determine whether MRI adds to the information provided by the less expensive and validated tests widely used to diagnose and monitor multiple myeloma (serum protein electrophoresis, β2-microglobulin, and radiographs). Patients and methods. We studied 51 patients with multiple myeloma (stage I in 14 cases, stage II in two cases, and stage III in 35 cases). Each patient underwent at least two MRI studies of the cervical, thoracic and lumbar spine during follow-up. Five patterns were identified: normal findings; and abnormal findings, with four subgroups: salt-and-pepper appearance, diffuse, focal and diffuse, and focal only, nodular or with a fracture. Results. The MRI pattern was correlated with the stage (according to Durie and Salmon); the β2-microglobulin level; the type of chain; and the response to therapy. An improvement in MRI findings correlated with a longer post-treatment remission. Conclusion. However, the images were difficult to interpret, and the various abnormalities seen were difficult to classify in some cases. Furthermore, analysis of individual data showed that some patients with quiescent, stage I disease had MRI findings suggestive of a poor prognosis and that some patients with stage III (advanced) disease had normal MRI findings. Consequently, except in patients with light-chain myeloma or plasmacytoma, it would probably be inappropriate to modify treatment decisions based on findings from MRI studies done to establish the initial diagnosis or to monitor the disease.