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 diffe rential enhancement ratio in the magnetic resonance (MR) imaging diffe rentiation of benign from malignant musculoskeletal masses. MATERIALS AND METHODS: Dynamic gadolinium-enhanced fast multiplanar spoiled grad ient-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 d etermined 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 e ach mass. RESULTS: Nine of 10 malignant masses showed rapid rim enhanc ement with delayed central fill-in. This enhancement pattern was absen t 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 b enign masses (P < .001). This difference was statistically significant The average maximum rate of enhancement was 3.41%/sec +/- 220 for mal ignant masses and 2.74%/sec +/- 2.46 for benign masses (P > .05). CONC LUSION: Intratumoral enhancement patterns of malignant and benign mass es differ because of differences in vascular architecture. These preli minary results suggest that the rim-to-center differential enhancement ratio has potential as an additional parameter for the MR imaging dif ferentiation of indeterminate musculoskeletal masses.