Imaging in osteomyelitis
From IDWiki
| Technique | Advantages | Disadvantages | Sn | Sp | Main Findings |
|---|---|---|---|---|---|
| X-ray | Inexpensive, reproducible, and accessible | Late diagnosis, confusing, and radiation | 43 to 75% | 75 to 83% | Lytic lesions, osteopenia, periosteal thickening, loss of trabecular architecture, new bone apposition |
| CT | Excellent spatial resolution | Cost, availability, radiation exposure | 67% | 50% | Blurring of fat planes, increased density of fatty marrow, periosteal reaction, cortical erosion or destruction, and sequestra, involucra, and intraosseous gas |
| US | Accessibility, inexpensive, real-time evaluation, guided aspiration/biopsy | Operator dependent, cannot image across cortical bone | To be determined | Elevated periosteum, soft tissue abscesses and fluid collections | |
| MRI | Excellent spatial resolution, early detection, assesses extent of tissues affected | Cost, availability, time requested | 82 to 100% | 75 to 96% | Acute: T1 shows low-signal-intensity medullary space; T2 shows high intensity surronuding inflammatory processes and edema; Gad enhances areas of necrosis Subacute: evidence of Brodie's abscess, single or multiple radiolucent abscesses; T1 shows central abscess cavity with low intensity; T2 shows high intensity of granulation tissue surrounded by low-intensity band of bone sclerosis (double-line) Chronic: T1 and T2 show low-intensity areas of devascularized fibrotic scarring in the marrow |
| Bone scan | Sensitive, available, relatively cheap, early detection | Nonspecific, further imaging required | ~85% | ~25% | Focal hyperperfusion or hyperemia or bone uptake |
| Bone+WBC scan | Reliable when clearly positive or negative | Need for two isotopes with multiple imaging sessions over several days, higher radiation exposure, often equivocal results, long examination time (days) | ~60% | ~80% | Localized area of increased uptake |
Specific Indications
- Post-fixation with hardware: WBC scan likely best, since none of the others can reliably distinguish between post-op changes and infection.
- Pressure ulcers: imaging (including MRI and WBC scan) cannot distinguish infection from bone remodeling due to pressure alone, with specificities decreasing to 15-60% range for all modalities
Further Reading
- Pineda C, Espinosa R, Pena A. Radiographic Imaging in Osteomyelitis: The Role of Plain Radiography, Computed Tomography, Ultrasonography, Magnetic Resonance Imaging, and Scintigraphy. Semin Plast Surg. 2009;23(2):080-089.
- Nuclear medicine imaging of bone infections. Nuc Med Comm. 2006;27:633–644.
