Chordomas are neoplasms that develop from intraosseous vestigial remnants of the notochord. The sacrum is the most common site accounting or fifty per cent of occurrences, followed by the clivus at thirty-five per cent. Clival chordomas may project into the sella or suprasellar regions. MR and CT techniques are both important in the differential diagnosis of these tumours. MR imaging best shows tumour infiltration and tumour origin in the clivus. Characteristic tumoural calcification is better identified with CT imaging. These tumours are often slightly hypointense on T1-weighted MR images and intensely enhanced following contrast administration (Fig. 24.19). Chondrosarcomas of the clivus may have an identical appearance on CT and MR studies.
Fig. 24.19 Clival chordoma. Contrast enhanced Tl-weighted sagittal MR image (a) showing an intensely enhancing large clival chordoma. The tumour compresses and displaces the pons posteriorly. Coronal CT image (b) in the same patient demonstrating globular calcification within the mass and clival destruction.
