Evaluation of the value of dynamic contrast-enhanced MRI for the diagnosis and follow-up of central cartilage tumors

Objectives: To evaluate the value of (dynamic) contrast-enhanced MRI for the diagnosis and follow-up of central cartilage tumors (CCT) of the proximal humerus, distal femur and proximal tibia. Materials & methods: 97 patients (44 +/- 11 years, 31men) with a CCT (histopathologically proven and/or > 2 years follow-up (5 +/- 3 years)) were retrospectively/consecutively included at the Ghent University Hospital (Belgium, 2003-2021). Thickness of the enhancing rim and dynamic contrast-enhanced MRI parameters of the entire tumor were calculated. Tumor volumes were calculated to assess tumor growth. Significant differences between enchondromas, atypical cartilaginous tumors, high-grade chondrosarcomas, tumors with and without growth at follow-up were evaluated and ROC-curves were analyzed. Results: A significant difference (p = 0.015) existed in enhancing rim thickness between high-grade chondrosarcomas and other groups. A ROC-curve with an AUC of 0.89 and cut-off value of 1.2 mm had a sensitivity of 100 % and a specificity of 64 % to identify high-grade chondrosarcomas. A significant correlation was found between the relative maximal enhancement (Rel-Emax) of the whole tumor compared to muscle and the absolute growth rate (rho = 0.75, p < 0.001). Lesions with a Rel-Emax < 1 remained stable or showed regression during follow-up (mean-0.1 +/- 0.3 ml/year). Lesions with a Rel-Emax between 1 and 2 showed little growth (mean + 0.2 +/- 0.2 ml/year), and lesions with a Rel-Emax > 2 had the highest growth rate (mean 0.4 +/- 0.2 ml/year). Conclusion: A thick enhancing rim > 1.2 mm has a high sensitivity to detect high-grade chondrosarcomas. The higher the Rel-Emax of the whole tumor compared to muscle, the higher the growth rate of a CCT.