Abstract
The bone marrow of the spine, pelvis and proximal femora was examined with MR imaging at diagnosis in 30 cases of multiple myeloma (MM), and during treatment on 69 occasions. The MR pattern was normal, focal or diffuse and correlated to stage. A tumour mass index (TMI) was calculated by estimating the total myeloma mass visualised at MR imaging. The TMI correlated significantly with stage, lytic bone lesions, serum calcium, serum β-2-microglobulin and survival. No abnormalities were seen at MR investigation in 4 of 6 patients classified as stage II because of osteoporosis only. Therapy efficacy evaluation with MR imaging corresponded to clinical evaluation on 54 of the 69 occasions. MR examination of bone marrow in MM patients can be used for tumour mass assessment, both at diagnosis and during follow-up. Valuable information can be obtained when the tumour mass is difficult to estimate using clinical criteria, e.g. in non-secretory MM or when osteoporosis is the only variable indicating an increase in the tumour mass.