eMedicine Specialties > Radiology > Brain/Spine

Chordoma: Imaging

Author: Paule Peretti, MD, Neuroradiologist, Radiological Department, Sainte Marguerite Hospital, France
Coauthor(s): Hervé Brunel, MD, Consulting Staff, Department of Neuroradiology, Montpellier of Pr Bonafé, France; Frédéric P Borrione, MD, Assistant Professor of Orthopedic Surgery, University of Marseilles; President, Center for Evaluation of Osteoarthritis Diseases, Marseilles, France; Guillaume Gorincour, MD, Staff Physician, Department of Neuroradiology, University Hospital of Marseilles, France
Contributor Information and Disclosures

Updated: Dec 23, 2008

Radiography

Findings

Radiographically, chordomas have 4 pathognomonic characteristics on plain film evaluation, as follows:

• Expansion of the bone
• Rarefaction
• Trabeculation
• Calcification

Degree of Confidence

Radiographs are neither specific nor sensitive for detecting chordoma. For intracranial chordomas, plain films are no longer used.

For sacrococcygeal and spinal chordomas, plain films are often the first examination, but CT scanning and MRI are necessary for the diagnosis.

False Positives/Negatives

Because portions of a chordoma may have little or no calcification present, even if a destructive clival lesion is observed on plain films, the size of the tumor may be grossly underestimated because the soft-tissue component is not visualized.

Computed Tomography

Findings

On CT scans, the tumor appears homogeneous, with a density comparable to that of muscles. Tumor appearance on contrast enhancement is heterogeneous. Calcification is found in less than one half of patients, and differentiation from sequestered bone fragments is difficult.^4,5,6

• Intracranial chordomas
  • The most characteristic appearance of intracranial chordoma is of a centrally located soft-tissue mass arising from the clivus and causing adjacent bone destruction.
  • Calcification is common.
  • Areas of low attenuation within the soft-tissue mass—representing the myxoid and gelatinous material found on pathologic examination—are occasionally found on CT scans.
  • CT scanning reliably demonstrates petrous apex involvement and lysis of the skull base foramina.
• Sacrococcygeal chordomas
  • The usual radiographic pattern is lytic, with frequent calcification or sequestered bone fragments.
  • Chordomas are often massive, well-delineated tumors that shift the fatty tissue of the pelvis and involve bone structures and the epidural area.
  • Peripheral sclerosis may be observed in approximately 50% of patients.
  • Frequently, a discrepancy is found between a large soft-tissue component and the area of bone involvement.
  • Regional lymph nodes are usually invaded.
  • The association of osteolytic lesions and soft masses involving the discs and the vertebrae suggests other diagnoses, such as neurofibromas, lymphomas, metastases, and plasmacytomas.
  • The most reliable sign of sacral chordomas is the destruction of several sacral vertebrae associated with a tissue mass anterior to the sacrum.
• Spinal chordomas
  • Infrequently, chordomas arise in the mobile (ie, cervical, thoracic, lumbar) spine (15%).
  • The cervical spine is the most common site for tumors, with a predominance in the C2 vertebra. The thoracic and lumbar areas of the spine are involved less frequently.
  • Initially, the presentation of chordoma on CT scan is of bone destruction centered in the vertebral body, with an associated, anteriorly or laterally situated, paraspinal soft-tissue mass that may contain calcification.
  • Chordomas that occur in vertebrae above the sacrum appear to originate in a single vertebral body, initially producing lytic changes and ultimately resulting in vertebral collapse.
  • The vertebral body is involved first; then, the pedicles, laminae, and spinal process become involved as well.
  • Adjacent intervertebral disc spaces are usually spared.
  • Occasionally, contiguous vertebrae are involved, with sparing of the discs.
  • Epidural extension of the tumor is usual.
  • Both CT scanning and MRI can define the extravertebral extension of the tumor. The main bulk of the tumor is usually anterior to the spine.

Degree of Confidence

CT scanning is essential for evaluating bony integrity, bone destruction, and calcifications or bone fragments within the lesion; for these uses, it is highly sensitive and accurate. MRI is the best technique to evaluate extension of the tumor.

Magnetic Resonance Imaging

Findings

Among imaging methods that contribute to the diagnosis, MRI is particularly reliable. T1- and T2-weighted sequences are needed before and after gadolinium injection. For clival chordomas, 3-dimensional gradient-echo T1-weighted sequences are helpful because they visualize the tumor in 3 planes within a short time and with a good analysis of tumoral signal.⁷

• Intracranial chordomas
  • Evaluation of the precise extent of the tumor and the degree of involvement of adjacent tissues is best performed by MRI. These attributes are relevant to diagnosis and choice of treatment (biopsy or surgical and/or radiosurgical treatment). MRI specifically shows tumor extension into critical structures, such as the cavernous sinuses, the circle of Willis, and the brainstem.
  • Chordomas originate from the midline, with varying degrees of lateral extension. This characteristic predilection for the midline may aid in the differential diagnosis.
  • Several authors have reported atypical sites of chordoma. They probably originate from ectopic notochord, and their prognosis differs from that of typical chordomas. The extension of chordomas is primarily posterior, with involvement of the pontine cistern and, occasionally, of the premedullary cistern. Anterior extension, which is also frequent, primarily occurs in massive tumors with significant destruction of the skull base. This can be anterosuperior to the sella turcica, displacing the pituitary gland, or anteroinferior to the nasopharynx or middle cranial fossa.
  • Overall, extension is primarily along the anteroposterior axis rather than laterally. However, some limited lateral extension commonly does occur into the cavernous sinuses, affecting treatment. It is observed in as many as 75% of patients.
  • Morphology and signal of the tumor are other elements in diagnosis.
  • The expansion of the bone in the early stage indicates that the tumor arises from bone and not from adjacent structures. This feature disappears as the tumor enlarges further.
  • Skull base chordomas are well delineated at the outset, since they displace adjacent structures; however, more advanced tumors become invasive and have a pseudomalignant appearance with bone erosion and soft-tissue invasion.
  • Most chordomas are isointense or demonstrate low signal on T1-weighted images. Some tumors an also demonstrate high signal, which is related on histologic examination to hemorrhage and mucinous collections. Tumoral signal on T1-weighted sequences is thus not entirely reliable.
  • Most chordomas exhibit high signal on T2-weighted images, which is also nonspecific.
  • Following gadolinium injection, chordomas usually show lobulated areas with a honeycomb appearance corresponding to low signal areas within the tumor. Chordoma signal is described as heterogeneous after gadolinium injection and on T1- and T2-weighted images. The pattern of contrast enhancement can be related to the pathologic features of the tumors, which are organized in lobules with mucinous and gelatinous contents. This may be a useful diagnostic sign. The borders of the tumor are better delineated with gadolinium injection.
• Chondromas may have the same radiologic appearance as chordomas. They originate from embryonic remnants of the primitive cartilage and tend to arise from and extend more laterally into the sellar and cerebellopontine-angle regions.
• Craniopharyngiomas have a different topography in addition to a relatively characteristic signal. The tumors are suprasellar, sellar, or infrasellar and are rarely at the level of the nasopharynx. Generally, the site is more anterior and superior, and extension is almost always posterosuperior (interpeduncular cistern).
• Invasive pituitary adenomas usually affect the sphenoid sinus, although in some patients they are posterior, in which case the hypophysis is not visible. Usually, the pontine cistern is not involved. Of course, clinical and biological data are the primary indications of pituitary origin, except in nonsecreting adenomas.
• Clivus meningiomas are differentiated easily from chordomas. They have a large dural attachment and do not appear similar to bone tumors. Homogeneity of their signal is an additional element.
• Chordomas can involve the petrous apex. Contrary to intrinsic petrous apex tumors (ie, rhabdomyosarcomas, metastases, plasmacytomas, cholesterol granulomas, epidermoid cysts), they originate from the midline.
• Aside from clinical data, few criteria exist for diagnosing lymphoma of the skull base. Similarly, bone metastases can be found in any part of the skull base with extensive osteolysis and a rapid course. Since skull base metastases are relatively infrequent in the absence of a primary neoplasm, differential diagnosis is easier. Neither type of tumor is frequent. Nasopharyngeal malignancies typically extend more anteriorly.
• Sacrococcygeal chordomas
  • MRI provides detailed multiplane information, with excellent contrast of the tumor and its surrounding anatomic structures. Tumoral extension is important to ascertain for preoperative planning and is observed as follows:
    • Proximal extension - Bone and sacral canal
    • Distal-lateral extension - Gluteus maximus, hamstrings, and sciatic nerve and notch
    • Anterior extension - Retroperitoneal lymph nodes and rectum
    • Posterior extension - Subcutaneous fat
  • On MRI, sacrococcygeal chordomas are lobulated tumors, typically with low to intermediate signal intensity on T1-weighted images and heterogeneous high signal intensity on T2-weighted images. The pattern of gadolinium enhancement is the same as for clival chordomas.

Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or magnetic resonance angiography scans. 

NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin;yellow spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see the FDA Public Health Advisory or Medscape.

Degree of Confidence

MRI is highly accurate in assessing soft-tissue extent of chordomas and in evaluating involvement of adjacent tissues.

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