Contrast-Enhanced MRI for Diagnosis of Abscess and Osteomyelitis
Contrast-enhanced MRI is strongly recommended for the diagnosis of abscess and osteomyelitis as it increases diagnostic confidence and better delineates abscesses, although it may not significantly increase sensitivity or specificity compared to non-contrast MRI. 1
Diagnostic Value of Contrast-Enhanced MRI
Benefits of Contrast Enhancement
Contrast-enhanced MRI significantly improves detection and delineation of:
- Abscesses (rim-enhancing collections)
- Soft tissue involvement extent
- Fistulas and sinus tracts
- Vascular complications 2
Contrast enhancement increases reader confidence in diagnosis by up to 46%, particularly for abscess detection 3
Gadolinium enhancement helps distinguish:
- Active inflammation from necrotic material
- Extent of bone involvement in chronic osteomyelitis
- Presence of subperiosteal or intraosseous abscesses 4
Clinical Applications
In pediatric patients, contrast-enhanced MRI is particularly valuable as infection may be limited to cartilaginous growth plates and epiphyses/apophyses, which can be occult on unenhanced sequences 2
Contrast enhancement guides:
- Surgical debridement planning
- Percutaneous drainage of fluid collections
- Differentiation between active infection and adequately treated infection 5
When Contrast May Not Be Necessary
If unenhanced MRI clearly shows absence of edema or fluid signal, contrast enhancement adds little value 3
In uncomplicated cases, fluid-sensitive sequences alone may be sufficient for diagnosis 1
Alternative Imaging Approaches
When MRI is Contraindicated
CT with IV contrast (rated 7/9 by ACR) can be used 1
- Useful for detecting periosteal reaction, bone destruction, and sinus tracts
- Superior to MRI for diagnosis of sequestra, foreign bodies, and gas
- Less sensitive for bone marrow pathology 2
Nuclear medicine studies:
- 3-phase bone scan with labeled leukocyte scan
- FDG-PET/CT for multifocal infection evaluation 1
Special Considerations
Hardware and Post-Surgical Settings
- Contrast-enhanced MRI with metal artifact reduction sequences is strongly recommended when hardware is present 1
Pediatric Patients
- MRI is strongly preferred over nuclear medicine studies due to radiation concerns 1
- Consider whole-body evaluation for multifocal osteomyelitis, more common in children under 6 years 1
Diagnostic Pitfalls to Avoid
- Difficulty distinguishing infection from reactive inflammation
- Potential confusion between osteomyelitis and bone infarction in sickle cell disease
- Differentiating osteomyelitis from Ewing sarcoma 1
- Artifacts from orthopedic hardware may limit evaluation
In conclusion, while non-contrast MRI has high sensitivity for osteomyelitis and abscess detection, contrast enhancement provides critical information about the extent of disease, presence of abscesses requiring drainage, and activity of infection, making it the preferred approach for comprehensive evaluation of suspected osteomyelitis and abscess.