State-of-the-Art Imaging in Human Chordoma of the Skull Base

Abstract

Purpose of review: Chordoma are rare tumours of the axial skeleton which occur most often at the base of the skull and in the sacrum. Although chordoma are generally slow-growing lesions, the recurrence rate is high and the location makes it often difficult to treat. Both computed tomography (CT) and magnetic resonance imaging (MRI) are crucial in the initial diagnosis, treatment planning and post-treatment follow-up.

Recent findings: Basic MRI and CT characteristics of chordoma were described in the late 1980s and early 1990s. Since then, imaging techniques have evolved with increased resolution and new molecular imaging tools are rapidly evolving. New imaging tools have been developed not only to study anatomy, but also physiologic changes and characterization of tissue and assessment of tumour biology. Recent studies show the uptake of multiple PET tracers in chordoma, which may become an important aspect in the diagnosis, follow-up and personalized therapy.

Summary: This review gives an overview of skull base chordoma histopathology, classic imaging characteristics, radiomics and state-of-the-art imaging techniques that are now emerging in diagnosis, treatment planning and disease monitoring of skull base chordoma.

Keywords: Benign notochordal cell tumour (BNCT); Chondrosarcoma; Chordoma; Computed tomography (CT); Diffusion-weighted imaging (DWI); Magnetic resonance imaging (MRI); Positron emission tomography (PET).

Fig. 1

Chordoma. Imaging of a chordoma at the craniocervical junction. Computed tomography (a) shows lysis of the lower clivus. Axial T2-weighted imaging (b) shows a heterogenous, mostly hyperintense mass at the midline of the lower clivus. There is anterior extension to the oropharynx. The mass is hypointense on T1-weighted imaging (c) with heterogenous contrast enhancement (d). Pathologic examination confirmed the diagnosis of chordoma

Fig. 2

Chordoma. Magnetic resonance imaging of a skull base chordoma arising at the clivus with compression of the brain stem. Axial T1-weighted imaging (a) shows a mass with mostly hypointense signal, a hyperintense focus (arrow) and heterogeneous contrast uptake (b, e). Axial FLAIR (c) shows heterogenous tumour intensity. T2-weighted imaging (c, f) shows mostly hyperintense signal intensity with linear foci of hypointensity. Pathologic examination confirmed the diagnosis of chordoma

Fig. 3

BNCT. Imaging of a well-defined intraosseous lesion in the base of the skull. CT imaging of the clivus in axial (a) and sagittal (b) plane shows normal bone trabeculation. There is no trabecular or cortical destruction. T2-weighted MRI imaging in axial plane (c) shows a hyperintense mass at the clivus, which is hypointense on T1-weighted imaging (arrow, d) and does not show contrast enhancement (e), as opposed to the physiological contrast enhancement of the pituitary gland. This tumour shows typical imaging characteristics of a benign notochordal cell tumour. However, there was no pathologic confirmation. On follow-up MRI after 1 year, the lesion was unchanged

Fig. 4

Chondrosarcoma. Imaging of skull base chondrosarcoma arising from the left lateral clivus with extension to the clinoid process, cavernous sinus and intracranial extension and compression on the left temporal lobe. Computed tomography (a) shows bone destruction with hyperdense fragments in the tumour mass, which corresponds with the typical ‘rings-and-arcs’ seen in chondroid tumours like chondrosarcoma. T2-weighted imaging (b) shows a heterogenous, mostly hyperintense mass. T1-weighted imaging (c) shows a hypointense mass with heterogenous enhancement (d). Pathologic examination of the tumour mass concluded chondrosarcoma WHO grade 1