Benign and malignant musculoskeletal masses: MR imaging differentiation with rim-to-center differential enhancement ratios

PURPOSE: To assess the diagnostic potential of the rim-to-center differential enhancement ratio in the magnetic resonance (MR) imaging differentiation of benign from malignant musculoskeletal masses. MATERIALS AND METHODS: Dynamic gadolinium-enhanced fast multiplanar spoiled gradient- recalled acquisition in the steady state imaging was performed to evaluate 17 bone and soft-tissue masses (10 malignant, seven benign) in 14 patients. The rim-to-center differential enhancement ratio was determined from images at the maximal enhancement rate. The difference in differential enhancement ratios between benign and malignant masses was evaluated and compared with the maximum rate of enhancement for each mass. RESULTS: Nine of 10 malignant masses showed rapid rim enhancement with delayed central fill-in. This enhancement pattern was absent in benign masses. The average rim-to-center differential enhancement ratio was 0.64 ± 0.26 for malignant masses and - 0.16 ± 0.33 for benign masses (P < .001). This difference was statistically significant. The average maximum rate of enhancement was 3.41%/sec ± 2.20 for malignant masses and 2.74%/sec ± 2.46 for benign masses (P > .05). CONCLUSION: Intratumoral enhancement patterns of malignant and benign masses differ because of differences in vascular architecture. These preliminary results suggest that the rim-to-center differential enhancement ratio has potential as an additional parameter for the MR imaging differentiation of indeterminate musculoskeletal masses.