What imaging is recommended to check for osteomyelitis (infection of the bone)?

From the Guidelines

To check for osteomyelitis, MRI is the preferred imaging modality due to its high sensitivity and specificity for detecting bone infection. MRI can identify bone marrow edema, soft tissue involvement, and abscess formation early in the disease process, often before changes are visible on other imaging techniques 1.

Key Points to Consider

• Plain radiographs should be obtained first as a baseline, but they have limited sensitivity and typically don't show changes until 10-14 days after infection onset 1.
• If MRI is contraindicated or unavailable, a triple-phase bone scan is a reasonable alternative with good sensitivity but lower specificity 1.
• CT scanning can help identify cortical bone destruction, sequestra, and soft tissue gas but is less sensitive than MRI for early infection 1.
• For diabetic foot infections or cases with metal implants where MRI artifacts may be problematic, a combination of plain films with nuclear medicine studies like labeled leukocyte scans (combined with bone marrow scans) may provide better diagnostic accuracy 1.
• PET/CT is increasingly used for chronic osteomyelitis evaluation due to its ability to distinguish between active infection and healing bone 1.

Additional Considerations

• Ultrasound (US) plays a complementary role in the evaluation of osteomyelitis, primarily for detection and characterization of soft-tissue infections 1.
• Nuclear medicine examinations, such as labeled leukocyte scans, have a role in cases where MRI is contraindicated or when infection is multifocal 1.
• The choice of imaging modality should be guided by the clinical context, including the presence of metal implants, diabetic foot infections, or other conditions that may affect image quality or interpretation 1.

From the FDA Drug Label

Technescan HDP Tc 99m is a diagnostic skeletal imaging agent used to demonstrate areas of altered osteogenesis in adult and pediatric patients. To check for osteomyelitis, order a bone scan using technetium-99m (IV), as it is a diagnostic skeletal imaging agent that can demonstrate areas of altered osteogenesis, which may indicate osteomyelitis 2.

• Key points:
  • Technetium-99m (IV) is used for skeletal imaging
  • It can demonstrate areas of altered osteogenesis, which may be associated with osteomyelitis
  • A bone scan using technetium-99m (IV) can be ordered to check for osteomyelitis

From the Research

Imaging Modalities for Osteomyelitis

To check for osteomyelitis, various imaging modalities can be employed, each with its own strengths and weaknesses. The choice of imaging technique depends on the stage of the disease, the location of the suspected infection, and the patient's overall condition.

• Plain Radiography: Should always be the first imaging modality used, as it provides an overview of the anatomy and pathologic conditions of the bone and soft tissues 3. However, its sensitivity is low in the early stages of disease 4.
• Magnetic Resonance Imaging (MRI): Is the most sensitive and specific imaging modality for detecting osteomyelitis, providing superb anatomic detail and accurate information on the extent of the infectious process and soft tissues involved 3, 5, 6, 4.
• Computed Tomography (CT) Scan: Can be useful in detecting early osseous erosion and documenting the presence of sequestrum, foreign body, or gas formation, but is generally less sensitive than other modalities for detecting bone infection 3.
• Ultrasonography: Is most useful in diagnosing fluid collections, periosteal involvement, and surrounding soft tissue abnormalities, and may provide guidance for diagnostic or therapeutic aspiration, drainage, or tissue biopsy 3.
• Scintigraphy: Including technetium-99m-d, l-hexamethylpropylene amine oxime labelled leucocytes, has high diagnostic accuracy for chronic osteomyelitis, especially when combined with a 99mTc-methylene diphosphonate bone scan 5, 7.
• Positron Emission Tomography (PET): Has high diagnostic accuracy, similar to MRI and SPECT, but its use may be limited by availability and radiation exposure 5.
• Single-Photon Emission Computed Tomography (SPECT): Has high diagnostic accuracy, similar to MRI and PET, and may be useful in detecting multifocal osseous involvement 5.

Considerations for Imaging Modalities

When choosing an imaging modality, consider the following factors:

• Location of suspected infection: MRI, PET, and SPECT have high diagnostic accuracy for osteomyelitis in various locations, while CT and radiography may be less sensitive 5.
• Stage of disease: Plain radiography may be less sensitive in early stages, while MRI and scintigraphy may be more useful in later stages 3, 4.
• Patient factors: Diabetes mellitus and cardiovascular disease increase the overall risk of acute and chronic osteomyelitis, and may affect the choice of imaging modality 4.