Neuroimaging of chordoma: MRI findings
Magnetic resonance imaging is a key method for assessing the internal structure of a chordoma. The tumor mass typically originates from the clivus (clivus). A detailed analysis of various pulse sequences reveals the following characteristic diagnostic patterns:
- Sagittal T1-weighted image (T1WI): These tomograms clearly demonstrate how the pathological tumor tissue partially replaces the normal hyperintense (bright) bone marrow. Additionally, pronounced destruction of the cortical layer (cortex) is clearly identified in the posterior aspects of the lesion.
- Axial T2-weighted image (T2WI): Chordomas are characterized by a predominantly hyperintense (high) MR signal. Against this bright background, thin internal septa (septae) with low signal intensity are visualized. It is this contrasting combination that forms a highly specific radiological pattern — the soap-bubble appearance ('soap-bubble' appearance).
- T1WI with intravenous contrast enhancement: Following the administration of a paramagnetic contrast agent, a patchy (patchy), markedly heterogeneous enhancement of the tumor tissue itself is noted, reflecting its complex internal structure.
Glomus Jugulare Tumour
In addition to chordoma, skull base neuroimaging frequently evaluates other vascular and tissue lesions, notably the glomus jugulare tumor. Its comprehensive diagnosis requires a combination of computed tomography (CT), MRI, and targeted angiography.
Computed tomography (CT)
On axial CT slices, the tumor demonstrates pronounced osseous changes indicative of aggressive local growth:
- Enlargement of the right jugular foramen (jugular foramen) is visualized.
- Bone tissue destruction is determined in the adjacent petrous part of the temporal bone (petrous bone), directly caused by the mass effect of the tumor node.
Magnetic resonance imaging (MRI)
On axial contrast-enhanced T1WI, this lesion is characterized by marked and intense contrast enhancement (markedly enhancing). A critical differential diagnostic sign is the presence of signal void areas within the lesion structure — the flow voids phenomenon. These specific areas directly correspond to dilated blood vessels within the tumor body.
Angiography
Classical angiography (in the basin of the right external carotid artery) convincingly confirms the presence of a developed network of dilated blood vessels feeding the tumor. These angiographic findings fully correlate with the flow voids previously detected on MR tomograms.
Briefly: answers to topical questions
What skull base neoplasms must clival chordoma be differentiated from?
Clival chordoma must be differentiated from:
- Chondrosarcoma (chondrosarcoma);
- Metastases;
- Infratentorial primitive neuroectodermal embryonic tumor (PNET) or medulloblastoma;
- Choroid plexus carcinoma (choroid plexus carcinoma);
- Ewing sarcoma (Ewing sarcoma);
- Lymphoma (lymphoma);
- Langerhans cell histiocytosis (Langerhans cell histiocytosis).
Which cranial nerves pass through the jugular foramen and can be compressed by a glomus tumor?
The following pass through the jugular foramen:
- Glossopharyngeal nerve (n. glossopharyngeus, IX pair);
- Vagus nerve (n. vagus, cranial nerve X);
- Accessory nerve (n. accessorius, cranial nerve XI).
Sources indicate that the glossopharyngeal nerve exits through the jugular foramen together with the vagus and accessory nerves.
What histological subtypes of chordoma are distinguished in pathomorphology?
Pathomorphology distinguishes:
- Chordoma, NOS — including chondroid and poorly differentiated chordoma;
- Dedifferentiated chordoma.
Additionally, within the framework of BNCT transformation processes, incipient chordoma (incipient chordoma) and classic chordoma are described.
In which parts of the axial skeleton, besides the skull base, is chordoma most commonly localized?
Aside from the skull base, chordoma most frequently affects the lower axial skeleton. Major locations include:
- Sacrococcygeal region — the favored location, accounting for 50% of cases. Sacral involvement is usually located below the level of S3.
- Cervical spine — the tumor is rare in other (mobile) segments of the spine, but most common in the cervical region.
Chordoma is the most common malignant tumor in the sacral and cervical regions.
To memorize the imaging features of chordoma: "Clivus in soapy foam" — the tumor originates from the clivus and produces a prominent "soap-bubble" sign on T2WI.
Class and exam questions
From which anatomical structure of the skull base does chordoma typically originate?
On MRI scans, especially in the sagittal projection, it is clearly visible that the tumor mass originates directly from the clivus (clivus).
What is the "soap-bubble" sign on MRI?
This is a specific MRI pattern of chordoma on T2-weighted images, where thin low-signal septae are visualized against the background of a generally hyperintense tumor tissue signal.
How does a glomus jugulare tumor appear on CT?
Axial CT scans reveal characteristic enlargement of the jugular foramen and destruction of the adjacent petrous bone.
What causes the "flow voids" areas in the imaging of a glomus tumor?
Areas of signal loss (flow voids) on MRI correspond to dilated tumor blood vessels, which is also reliably confirmed by angiography in the external carotid artery basin.
What else to study on this topic
- Mechanisms of replacement of normal hyperintense bone marrow with pathological tumor tissue on T1WI.
- Specific features of detecting cortical bone destruction in the posterior skeletal structures during neoplasm growth.
- Comparative analysis of enhancement: patchy enhancement in chordoma versus marked enhancement in glomus tumor.
- Physics of the MR flow void phenomenon in dilated blood vessels.
- Topographic anatomy of the clivus and jugular foramen in the context of diagnostic radiology.
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