Diagnostic imaging of malignant cartilage tumors.

We compared the diagnostic capabilities of CT and MRI in the study of malignant cartilage tumors. Information about the characterization and the intra-/extraosseous spread of these lesions is of primary importance in the preoperative planning. Besides peripheral chondrosarcomas, arising from an osteochondroma and central chondrosarcomas, which are the most common malignant cartilaginous tumors, we also considered secondary, periosteal, dedifferentiated, clear cells and mesenchymal chondrosarcomas. Our study was performed using a standard MRI and CT protocol; in some cases, the examination was completed by the intravenous administration of a contrast agent. High contrast T2-weighted GE images can perfectly depict and differentiate the cartilage cap of an osteochondroma from the adjacent soft tissues. Evaluation of the growth of exostosis and of the thickness of its cap is essential in the assessement of malignant transformation. Both CT and MRI provide important information about peculiar aspects of the cartilaginous matrix such as the shape of calcifications-ossifications and lobulated growth, septa, septal enchancement and necrotic intratumoral areas, furthermore, CT perfectly shows the patterns of bone destruction. MRI should be considered as the most reliable imaging technique for the locoregional staging of malignant bone tumors thanks to its spatial and contrast resolution. CT plays a major role in the characterization of most bone tumors, especially those with a cartilaginous matrix.