Vertebral Osteomyelitis¶
Definition¶
Vertebral osteomyelitis refers specifically to infection of the vertebral body bone. In practice, it almost always coexists with discitis (spondylodiscitis) in pyogenic infections - in adults, infection usually starts at the vertebral endplate and spreads to the disc, whereas in children it begins in the disc and extends to the adjacent endplates. The term is used when the primary pathology is centered in the vertebral body, particularly in granulomatous infections (tuberculosis, brucellosis, fungal) where disc involvement may be delayed or minimal.
Imaging Findings¶
MRI¶
- T1-weighted — Replacement of normal fatty marrow signal with low signal in one or more vertebral bodies
- T2-weighted/STIR — High signal within the affected vertebral body
- Post-contrast — Enhancement of the vertebral body, which may be diffuse or peripheral (rim-enhancing abscess within the body)
- Endplate changes — Erosion and irregularity of the endplates adjacent to the disc
CT¶
- Cortical erosion and endplate destruction
- Lytic areas within the vertebral body
- Paravertebral soft tissue extension
- Sclerosis in subacute/chronic phases (reactive new bone formation)
Distinguishing from Modic Type 1 Changes¶
| Feature | Vertebral Osteomyelitis | Modic Type 1 |
|---|---|---|
| Endplate cortex | Destroyed, irregular | Intact |
| Disc signal | Increased T2, enhancement | Normal or mild dehydration |
| Intranuclear cleft | Lost | Preserved |
| Paravertebral tissue | Abnormal (edema, abscess) | Normal |
| Enhancement pattern | Disc + endplate + soft tissue | Endplate only |
| Clinical | Fever, elevated ESR/CRP | Back pain, no systemic symptoms |
Clinical Pearl
The most challenging differential diagnosis is distinguishing early spondylodiscitis from Modic Type 1 degenerative endplate changes — both show endplate marrow edema on MRI. The critical distinguishing features are: disc enhancement and increased T2 signal (infection), endplate cortical destruction (infection), paravertebral soft tissue abnormality (infection), and clinical context (fever, elevated inflammatory markers). When in doubt, follow-up MRI and inflammatory markers can clarify.
Key Points¶
- Vertebral osteomyelitis almost always coexists with discitis in pyogenic infections
- MRI shows marrow replacement, endplate destruction, and disc involvement
- Distinguish from Modic Type 1 changes by disc signal, endplate cortex integrity, and soft tissue involvement
- CT-guided biopsy establishes the organism
- Granulomatous infections (TB, brucella) may show vertebral body involvement with relative disc preservation early
References¶
- Hall WA, Graeber A, Cecava ND. Vertebral Osteomyelitis. In: StatPearls. Treasure Island (FL): StatPearls Publishing; updated 2024 Nov 25. https://www.ncbi.nlm.nih.gov/books/NBK532256/
- Berbari EF, Kanj SS, Kowalski TJ, et al. 2015 Infectious Diseases Society of America (IDSA) Clinical Practice Guidelines for the Diagnosis and Treatment of Native Vertebral Osteomyelitis in Adults. Clin Infect Dis. 2015;61(6):e26-46. https://pubmed.ncbi.nlm.nih.gov/26229122/
- Zimmerli W. Clinical practice. Vertebral osteomyelitis. N Engl J Med. 2010;362(11):1022-1029. https://pubmed.ncbi.nlm.nih.gov/20237348/
- Expert Panel on Neurological Imaging; Ortiz AO, Levitt A, Shah LM, et al. ACR Appropriateness Criteria® Suspected Spine Infection. J Am Coll Radiol. 2021;18(11S):S488-S501. https://pubmed.ncbi.nlm.nih.gov/34794603/
- Crombé A, Fadli D, Clinca R, et al. Imaging of Spondylodiscitis: A Comprehensive Updated Review—Multimodality Imaging Findings, Differential Diagnosis, and Specific Microorganisms Detection. Microorganisms. 2024;12(5):893. https://pmc.ncbi.nlm.nih.gov/articles/PMC11123694/
- Spondylodiscitis. Radiopaedia.org. https://radiopaedia.org/articles/spondylodiscitis