12Ağu
Radiological Approach to Infectious Diseases of the Spine

1. Terminology

  • Discitis: Infection limited to the intervertebral disc
  • Spondylitis: Infection of the vertebral body
  • Spondylodiscitis: Involvement of both the intervertebral disc and adjacent vertebral bodies

2. Etiology and Pathogenesis

  • Hematogenous spread – the most common route (especially Staphylococcus aureus)
  • Direct inoculation – post-surgical infections
  • Contiguous spread – from psoas abscess, retroperitoneal infections, etc.

3. Imaging Modalities

Magnetic Resonance Imaging (MRI)

  • Gold standard for diagnosis
  • Early findings: Low signal on T1-weighted images, high signal on T2/STIR
  • Contrast-enhanced MRI: Demonstrates epidural/paraspinal abscesses and granulation tissue
  • Diffusion-weighted imaging (DWI): Differentiates abscess from necrotic tissue

Computed Tomography (CT)

  • Useful for visualizing bone erosion, destruction, and sequestrum
  • Guides biopsy/aspiration procedures

Plain Radiography

  • Usually normal in early stages
  • Late findings include disc space narrowing, vertebral endplate erosion

4. Differential Diagnosis

  • Modic changes (especially Type 1)
  • Metastatic lesions
  • Traumatic vertebral fractures
  • Osteoporotic changes

5. Summary of Radiological Findings

ModalityTypical Findings
MRI T1Loss of vertebral and disc signal
MRI T2/STIRHigh signal, marrow/soft tissue edema
Contrast MRIEnhancement of the disc and adjacent vertebra; possible epidural collection
CTEndplate erosion, bone destruction

6. Clinical Pearls

  • Disc involvement on MRI strongly suggests infection (rare in tumors)
  • Epidural abscess requires urgent surgical consultation
  • In early stages, MRI findings may be subtle; repeat imaging if clinical suspicion remains high

Conclusion

MRI is the primary modality for evaluating infectious diseases of the spine. Early and accurate diagnosis facilitates prompt initiation of antimicrobial and/or surgical treatment, reducing morbidity and mortality.

CASE

A 62-year-old female patient with a history of diabetes presented with low back pain. MRI was performed.