Radiography: where the search begins
Radiological examination (plain radiography) is rarely used as the definitive diagnostic method when a spinal oncological process is suspected. Nevertheless, this method is often the first step in the evaluation. The reason lies in the non-specific nature of symptoms: patients present with typical back pain, while primary benign bone neoplasms may remain asymptomatic for years, discovered only as an incidental finding after a prior trauma.
On standard radiographs, a number of important indirect signs of involvement can be noted:
- Smoothing of the physiological cervical lordosis or the appearance of torticollis (characteristic of intramedullary lesions at the cervical level).
- Scoliotic deformity (accompanies virtually all large spinal cord tumors, regardless of their histological structure).
If a spinal neoplasm is actively increasing in size (e.g., in myxopapillary ependymoma), it begins to exert pressure on surrounding bone structures. This leads to so-called pressure erosion (pressure erosion). On a radiograph, this process manifests as widening of the bony spinal canal—an extremely important diagnostic marker.
Another characteristic phenomenon is scalloping (scalloping / festooning). It represents a specific deformation of the posterior surface of the vertebral bodies, predominantly at the lower thoracic and upper lumbar segments. In addition, in intradural extramedullary processes prone to invading the paravertebral and epidural spaces, radiographs may reveal widening of the intervertebral foramina (spinal foramina), as well as areas of calcification inside the tumor itself.
Computed tomography: focus on bones
Computed tomography (computed tomography) is recognized as the optimal tool for a detailed study of the bony framework of the spinal column. The use of multislice scanners (MDCT) makes it possible to rapidly acquire a dataset covering a significant length of the spine.
Using multiplanar reconstruction algorithms, a radiologist can generate high-precision 2D images in three orthogonal planes. This is critically important for:
- Assessing the integrity of the bone cortex and identifying even minimal zones of destruction.
- Detecting dense inclusions, i.e., calcifications.
- Visualizing widened intervertebral foramina (neuroforamina) and an enlarged spinal canal (which often accompanies intradural tumors).
It is worth noting that the radiological presentation of many bone lesions is extremely similar. Therefore, despite the high resolution of modern scanners, to definitively confirm the diagnosis, physicians often have to resort to puncture biopsy. In such cases, computed tomography acts as an ideal navigator, allowing the needle to be safely guided to the pathological lesion.
Magnetic resonance imaging: the gold standard
Magnetic resonance imaging (magnetic resonance imaging) confidently holds the position of the method of choice in the diagnosis of oncological diseases of the spine and spinal cord. Unlike other methods, MRI provides comprehensive information about the state of neural structures and the epidural space, and also plays a crucial role in assessing bone involvement itself.
To achieve maximum image quality, modern technical solutions are applied:
- Multichannel phased-array coils (phased-array coils) provide a wide field of view (FOV).
- Parallel acquisition technologies (parallel acquisition) combined with special reconstruction algorithms reduce scan time, increase the signal-to-noise ratio (SNR), and minimize artifacts.
- It is possible to perform comprehensive screening of the entire spine and even the whole body (full-spine and whole-body MRI) in a single visit.
The standard MRI protocol is based on a combination of sagittal and axial slices. Each pulse sequence serves a specific purpose:
- T2-weighted images (T2-WI): unmatched in finding intramedullary (intraspinal) nodes.
- T1-weighted images (T1-WI): have high sensitivity to bone marrow changes without fat suppression, making them indispensable when searching for vertebral metastases.
- STIR (short tau inversion recovery) and similar fat-suppression modes: significantly improve the visualization of specific bone marrow lesions.
- FLAIR (fluid-attenuated inversion recovery): suppresses the high signal from cerebrospinal fluid, helping to recognize subtle lesions inside the spinal cord.
- GRE (gradient-echo): excellent at capturing hemorrhagic components that often accompany tumors. An additional sagittal out-of-phase GRE sequence is used for screening metastatic lesions, based on the physiological ratio of fat and water protons in the cancellous bone of an adult.
Briefly: answers to topical questions
What are the differences in radiological features between intramedullary and extramedullary spinal cord tumors?
Radiological features of intramedullary and intradural extramedullary tumors differ in localization and propagation pattern.
| Method / feature | Intramedullary tumors | Intradural extramedullary tumors |
|---|---|---|
| Radiography | In cervical tumors, smoothing of cervical lordosis and torticollis are possible | Widening of the intervertebral foramina and the presence of intratumoral calcifications are possible |
| MRI | T2-WI outperform other sequences in detecting intramedullary tumors; FLAIR is useful for detecting subtle intramedullary lesions | MRI evaluates the tumor and its extension; some tumors, such as schwannomas, may have a dumbbell shape |
| Propagation features | A growing tumor can expand the spinal canal due to pressure erosion | Tumors can extend into the epidural and paravertebral spaces; widening of the intervertebral foramina is possible |
Which histological types of primary spinal tumors are most common?
The most frequent histological types of primary spinal tumors are multiple myeloma, plasmacytoma, and hemangioma.
- Multiple myeloma (multiple myeloma) and plasmacytoma (plasmacytoma) are the most frequent diagnoses overall among primary tumors.
- Vertebral hemangioma (vertebral haemangioma) is the most common benign spinal tumor.
- Chordoma (chordoma) is the most frequent malignant tumor in the cervical and sacral regions.
- Osteosarcoma (osteosarcoma) ranks third in frequency among malignant neoplasms.
Which specific histological types of tumors most commonly cause widening of the intervertebral foramina?
Widening of the intervertebral foramina can be observed in intradural tumor pathology, especially in nerve sheath tumors.
- Nerve sheath tumors include schwannoma (schwannoma) and neurofibroma (neurofibroma).
- Schwannomas can have a dumbbell shape, extending into the intradural and epidural spaces.
- With nerve or nerve sheath tumors, contrast enhancement and widening of the intervertebral foramina are possible.
Overall, in intradural tumor pathology, CT may reveal widening of the bony spinal canal and intervertebral foramina.
What are the absolute and relative contraindications to spinal MRI?
Contraindications to MRI are divided into absolute, associated with exposure to a powerful magnetic field, and relative.
- Absolute contraindications: presence of electronic implantable devices (pacemaker, middle ear implant system, insulin pump) and ferromagnetic foreign bodies (metal shrapnel in organs, inside or near the eyeball, cerebral vessel clips).
- Relative contraindications: claustrophobia (fear of enclosed spaces).
Modern models of implantable devices may be MRI-compatible, making the examination possible.
What are the pathways of malignant tumor metastasis to the spine?
Metastasis of malignant tumors to the spine and spinal cord occurs via hematogenous and cerebrospinal fluid (CSF) pathways.
- Hematogenous pathway — mediated by venous tumor emboli penetrating valveless venous plexuses (e.g., Batson vertebral plexus — Batson vertebral plexus).
- CSF pathway — spread of primary CNS tumors along the cerebrospinal fluid pathways with the formation of leptomeningeal or drop metastases (drop metastasis).
Class and exam questions
Why is radiography performed first if it is not the modality of choice?
Patients with neoplasms often initially present with back pain or sustain injuries. Primary benign bone lesions are often asymptomatic in the early stages and are incidental findings on baseline radiographs.
What is vertebral scalloping?
This is a pathological scalloped deformation of the posterior surface of the vertebral bodies. This symptom is most commonly detected in the lower thoracic and upper lumbar spine in growing spinal cord tumors.
Which MRI sequence best demonstrates intramedullary tumors?
For targeted detection and evaluation of pathologies within the spinal cord itself, T2-weighted images are optimally used.
Why is a biopsy needed if modern MRI and CT are available?
Many bone lesions have a similar radiological presentation. A CT-guided biopsy is often necessary to determine the exact histological structure and choose treatment tactics.
What else to study on this topic
- Differential diagnostic imaging of bone marrow metastases
- Radiological semiotics of myxopapillary ependymoma
- Physical principles of the out-of-phase effect in MRI
- Features of extramedullary tumor spread
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