[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Radiology](https://durgical.com/en/radiology/) › [Neuroradiology](https://durgical.com/en/radiology/areas/neuro/) › Spine MRI: cord compression, disc and infection

# Spine MRI: cord compression, disc and infection

- Finding

MRI is the scan that shows the spinal cord and nerves. When back pain comes with weakness, numbness or bladder problems, it is needed the same day.

Updated Nov 13, 2026

## Key points

- MRI is the study of choice for suspected cord compression, cauda equina syndrome and spinal infection.
- Image the whole spine in suspected metastatic compression: lesions are often multiple.
- Infection crosses the disc; metastases usually spare it.
- Function at the time of treatment predicts outcome: scan the same day.

## What it is

Spine MRI shows the spinal cord, the nerve roots, the discs, the bone marrow and the epidural space, which X-rays and even CT show poorly. Three emergencies depend on it: spinal cord compression (often from metastases to the vertebrae), cauda equina syndrome (usually a large central disc in the lower lumbar spine) and spinal infection (epidural abscess or discitis with vertebral osteomyelitis). In each one the outcome depends on how much function the patient still has when treated, so the scan is done urgently, of the right region and usually with contrast when tumour or infection is possible. For ordinary low back pain without red flags, early MRI changes nothing and often shows harmless age-related disc changes.

## What it looks like

- Normal marrow is bright on T1 because of fat; tumour or infection replaces the fat and turns the vertebral body dark on T1.
- Metastatic compression: dark T1 vertebral body, often a pedicle or posterior element involved, an epidural soft-tissue mass pushing on the cord.
- Cord oedema or injury is bright on T2 inside the cord at the level of compression.
- Disc herniation: disc material beyond the edge of the vertebral endplates; most common at L4-L5 and L5-S1.
- Cauda equina: a large central disc or mass fills the lumbar canal and crowds the nerve roots below the conus (which normally ends around L1-L2).
- Epidural abscess: an epidural collection, bright on T2, with rim or diffuse enhancement after gadolinium, compressing the cord or roots.
- Discitis-osteomyelitis: bright, enhancing disc with eroded endplates and dark T1 marrow on both sides of the disc.
- Tuberculous spondylitis tends to spread under the ligaments over several levels, with large paraspinal abscesses and relative sparing of the disc.

## Why it looks that way

- T1 shows anatomy and marrow fat; T2 shows fluid, oedema, pus and the CSF around the cord.
- Gadolinium enhances tissue with a rich blood supply or inflammation: tumour, abscess wall, infected disc.
- Metastatic disease reaches the vertebral body through the blood and often spares the disc; bacterial infection usually starts at the endplate and crosses the disc.

| Problem | Key MRI finding | Contrast? | Urgency |
| --- | --- | --- | --- |
| Metastatic cord compression | Dark T1 vertebra, epidural mass, cord compressed | Helpful | Emergency, whole spine |
| Cauda equina syndrome | Large central lumbar disc or mass crowding the roots | Usually not needed | Emergency |
| Epidural abscess | T2-bright epidural collection with rim enhancement | Yes | Emergency |
| Discitis-osteomyelitis | Enhancing disc, eroded endplates, dark T1 marrow | Yes | Urgent |
| Disc herniation with radiculopathy | Disc compressing a root at the matching level | No | Routine unless deficit progresses |

## Differential and pitfalls

- Metastases can sit at several levels: image the whole spine when cord compression from cancer is suspected.
- Disc bulges and degenerative changes are common in people without pain; correlate the level and side with the exam.
- Fever may be absent in epidural abscess; back pain with neurological signs in a diabetic, injecting drug user or patient with a recent procedure needs MRI with contrast.
- Degenerative endplate changes (Modic) can mimic infection; the disc and the clinical picture help, and biopsy may be needed.
- Plain X-rays are often normal early in metastatic and infectious disease and do not exclude either.

## Next step

- New weakness, sensory level, saddle numbness or bladder or bowel dysfunction: emergency MRI (whole spine if cancer is possible) and call the spine surgeon or neurosurgeon.
- Suspected cauda equina: check the post-void residual with a bladder scan while arranging the MRI; do not wait for retention.
- Suspected infection: blood cultures and inflammatory markers before antibiotics when possible; MRI with gadolinium; image-guided biopsy if cultures are negative.
- MRI not possible (unsafe implant, unavailable): CT myelography or CT, discussed with the radiologist.
- Low back pain without red flags: no early MRI; review and reassess.

## Memory aid

Infection eats the disc, tumour spares it.

## Test yourself

Think of the answer, then tap the question to see it.

## Why does a vertebra invaded by tumour look dark on T1 MRI?

Normal adult marrow contains fat, which is bright on T1; tumour cells replace the fat, so the involved vertebra turns dark.

## Which MRI feature helps tell discitis-osteomyelitis from vertebral metastasis?

Pyogenic infection involves the disc (bright, enhancing, with eroded endplates on both sides), while metastases usually spare the disc.

## Why should the whole spine be imaged in suspected metastatic cord compression?

Metastases are often present at several levels, and a second compression may be clinically silent or masked by the first.

## What MRI finding characterises a spinal epidural abscess?

An epidural collection that is bright on T2 and shows rim or diffuse enhancement after gadolinium, often next to discitis, compressing the cord or nerve roots.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/radiology/spine-mri-cord-compression-disc-and-infection/)

## Elsewhere in DurgiPedia

- [Spinal cord syndromes: complete, Brown-Séquard, central, anterior](https://durgical.com/en/clinical-exam/spinal-cord-syndromes-complete-brown-sequard-central-anterior/)
- [Spine examination: the Adams forward-bend test and Schober test](https://durgical.com/en/clinical-exam/spine-examination-the-adams-forward-bend-test-and-schober-test/)
- [Deep tendon reflexes and their grading](https://durgical.com/en/clinical-exam/deep-tendon-reflexes-and-their-grading/)
- [Sensory examination: modalities and dermatomes](https://durgical.com/en/clinical-exam/sensory-examination-modalities-and-dermatomes/)

## Connections

## Related 6

- [Cervical spine imaging in trauma: who needs it](https://durgical.com/en/radiology/cervical-spine-imaging-in-trauma-who-needs-it/)
- [MRI: T1, T2, FLAIR and diffusion](https://durgical.com/en/radiology/mri-t1-t2-flair-and-diffusion/)
- [MRI safety: implants, metal and gadolinium](https://durgical.com/en/radiology/mri-safety-implants-metal-and-gadolinium/)
- [Brain MRI: when it beats CT](https://durgical.com/en/radiology/brain-mri-when-it-beats-ct/)
- [Bone lesions: aggressive or not](https://durgical.com/en/radiology/bone-lesions-aggressive-or-not/)
- [Imaging in osteomyelitis](https://durgical.com/en/radiology/imaging-in-osteomyelitis/)

## Related conditions 7

- [Malignant spinal cord compression](https://durgical.com/en/conditions/malignant-spinal-cord-compression/)
- [Cauda equina syndrome](https://durgical.com/en/conditions/cauda-equina-syndrome/)
- [Spinal epidural abscess](https://durgical.com/en/conditions/spinal-epidural-abscess/)
- [Lumbar Disc Herniation](https://durgical.com/en/conditions/lumbar-disc-herniation/)
- [Vertebral osteomyelitis](https://durgical.com/en/conditions/vertebral-osteomyelitis/)
- [Spinal tuberculosis (Pott disease)](https://durgical.com/en/conditions/spinal-tuberculosis/)
- [Degenerative cervical myelopathy](https://durgical.com/en/conditions/degenerative-cervical-myelopathy/)

[← All of radiology](https://durgical.com/en/radiology/)

Educational content; it does not replace a radiologist's report and is not a clinical instruction. Each study is ordered on the patient's assessment and your institution's protocols.

Sources: [Spinal Cord Compression](https://www.ncbi.nlm.nih.gov/books/NBK557604/) (StatPearls (NCBI Bookshelf), 2023); [Cauda Equina and Conus Medullaris Syndromes](https://www.ncbi.nlm.nih.gov/books/NBK537200/) (StatPearls (NCBI Bookshelf), 2023); [Spinal Epidural Abscess](https://www.ncbi.nlm.nih.gov/books/NBK441890/) (StatPearls (NCBI Bookshelf), 2025).

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Source: https://durgical.com/en/radiology/spine-mri-cord-compression-disc-and-infection/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/radiology/spine-mri-cord-compression-disc-and-infection/