Dynamic contrast-enhanced MR imaging for differentiation between enchondroma and chondrosarcoma.

OBJECTIVES: To determine whether dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) can differentiate benign from malignant cartilage tumours compared to standard MRI. To investigate whether a cutoff value could be determined to differentiate enchondroma from low-grade chondrosarcoma (CS) more accurately.

METHODS: One hundred six patients were included in this retrospective study: 75 with enchondromas (mean age = 41 years) and 31 with CS (mean age = 47 years). Within this population, a subgroup of patients was selected with the tumour arising in a long bone. At the time of diagnosis, the tumours were evaluated on MRI, including standard MRI, DCE-MRI, and region-of-interest (ROI) analysis to obtain information on tumour vascularisation and perfusion.

RESULTS: The main cutoff value to differentiate enchondroma from CS contained a two-fold more relative enhancement compared with muscle, combined with a 4.5 (= 76°) slope value, with 100 % sensitivity and 63.3 % specificity. The prediction of CS diagnosis with DCE-MRI had 93.4 % accuracy. The accuracy of the standard MRI parameters was equal to the DCE-MRI parameters.

CONCLUSIONS: Standard MRI and DCE-MRI both play an important and complementary role in differentiating enchondroma from low-grade CS. A combination of both imaging techniques leads to the highest diagnostic accuracy for differentiating cartilaginous tumours.

KEY POINTS: • DCE-MRI plays an important role in differentiating benign from malignant cartilage tumours. • Retrospective study defined a threshold for 100 % detection of chondrosarcoma with DCE-MRI. • The threshold values were relative enhancement = 2 and slope = 4.5. • One hundred per cent chondrosarcoma detection corresponds with 36.7 % false-positive diagnosis of enchondroma. • Standard MRI is complementary to DCE-MRI in differentiating cartilaginous tumours.