Intracranial chordoma is a locally aggressive and relatively rare tumor of the skull base that is thought to originate from embryonic remnants of the primitive notochord. Both computed tomography (CT) and magnetic resonance (MR) imaging are usually required for evaluation of intracranial chordomas due to bone involvement and the proximity of these tumors to many critical soft-tissue structures. At CT, intracranial chordoma typically appears as a centrally located, well-circumscribed, expansile soft-tissue mass that arises from the clivus with associated extensive lytic bone destruction. However, MR imaging is the single best imaging modality for both pre- and posttreatment evaluation of intracranial chordoma. On T1-weighted MR images, intracranial chordomas demonstrate intermediate to low signal intensity and are easily recognized within the high-signal-intensity fat of the clivus. On T2-weighted MR images, they characteristically demonstrate very high signal intensity, a finding that likely reflects the high fluid content of vacuolated cellular components. Moderate to marked enhancement is common and often heterogeneous on contrast material-enhanced images. Combination treatment with radical surgical resection and proton beam radiation therapy achieves the best results.
Copyright RSNA, 2003