Pyogenic Osteomyelitis



  • Definition: Bacterial suppurative infection of vertebrae and intervertebral disc

  • Synonyms: Pyogenic spondylodiscitis, disc space infection


  • Ill-defined hypointense T1 vertebral marrow with loss of endplate definition on both sides of disc

  • Loss of disc height and abnormal disc signal

  • Destruction of vertebral endplate cortex

  • Vertebral collapse

  • Paraspinal ± epidural infiltrative soft tissue ± loculated fluid collection

  • Follow-up MR

    • Should focus on soft tissue findings

    • No single MR imaging parameter is associated with clinical status

Top Differential Diagnoses

  • Degenerative endplate changes

  • Tuberculous vertebral osteomyelitis

  • Spinal neuropathic arthropathy


  • Predisposing factors

    • Intravenous drug use

    • Immunocompromised state

    • Chronic medical illnesses (renal failure, cirrhosis, cancer, diabetes)

  • Staphylococcus aureus is most common pathogen

Clinical Issues

  • Acute or chronic back pain

  • Focal spinal tenderness

  • Fever

  • ↑ ESR, ↑ CRP, ↑ WBC

Sagittal T1WI MR in a patient with a history of lumbar surgery shows findings of disc space infection at L4-L5 with hypointense marrow, vertebral collapse, endplate erosion, disc space loss, and epidural phlegmon.

Sagittal T1WI C+ MR demonstrates enhancing vertebral bodies and intervening disc. There is an epidural abscess extending from L4-L5 to S1, consistent with pyogenic vertebral osteomyelitis. Severe central canal narrowing is present at L4-L5.

Sagittal STIR MR shows increased fluid in the retropharyngeal/prevertebral space . Marrow edema in C6 and C7 vertebral bodies is seen . There is fluid signal within the disc space with irregularity along the endplate cortical margins.

Sagittal T1WI C+ FS MR shows homogeneously enhancing epidural phlegmon at the C6-C7 level causing mass effect on the cord. C6 & C7 vertebral bodies exhibit avid homogeneous enhancement . Note the prevertebral, enhancing soft tissues representing phlegmon.



  • Pyogenic spondylodiscitis, disc space infection

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