Computed tomography characteristics of multiple myeloma and other osteolytic metastatic bone lesions.

BACKGROUND: Differentiation of multiple myeloma (MM) from osteolytic metastatic (OM) bone lesions may be critical in patients with lytic bone lesions but can be challenging for radiologists.

PURPOSE: To determine whether computed tomography (CT) can be used to distinguish between MM and other OM bone lesions.

MATERIAL AND METHODS: In this retrospective study, 320 lesions of 207 patients diagnosed with MM or OM, based on biopsy or clinical examination, were evaluated. Eight qualitative features were evaluated by two radiologists blinded to the diagnoses. The chi-square and Fisher exact tests, and logistic regression analysis, were used to evaluate the relationships between the CT findings and diagnoses.

RESULTS: High-density areas were more common in OM than MM lesions (85.2% and 19%, P  < 0.001), as were perilesional sclerosis (38.9% vs. 13.2%, P  < 0.001), heterogeneity (on non-contrast CT images, 60% vs. 19.1%, P  < 0.001; on contrast enhanced CT images, 80.6% vs. 28.2%, P  < 0.001), and ill-defined margins (34.6% vs. 9.1%, P  < 0.001). Similarly, OM lesions showed high-density areas more than MM in evaluation of skeletal system subgroups (vertebrae, 93.8% vs. 29.8%, P  < 0.0001; thoracic cage bones, 69.6% vs. 19.2%, P  < 0.001; pelvic bones and sacrum, 84.8% vs. 7.7%, P  < 0.001; peripheral skeletal bones, 81.5% vs. 8.3%, P  < 0.001). Logistic regression analysis revealed that the presence of a high-density area in the lesion increased the probability of a metastasis 25.88-fold (R2  = 0.516, P  < 0.001).

CONCLUSION: MM and OM lesions can be differentiated by CT; OM lesions exhibit high- density areas.