From the Guidelines
Magnetic Resonance Imaging (MRI) is the most sensitive and specific imaging modality for evaluating soft tissue and bone infections, particularly for detecting inflammation, fasciitis, myositis, and areas of necrosis. When considering the best imaging modality to evaluate for infection, it is essential to weigh the strengths and limitations of each option.
Key Considerations
- MRI offers multiplanar capability and is favored for its greater sensitivity in detecting inflammation and associated complications 1.
- Ultrasound (US) is valuable in detecting soft-tissue fluid collections, foreign bodies, and joint effusions, especially in young children due to its lack of radiation and no need for sedation 1.
- Computed Tomography (CT) is well-suited for delineating the anatomic extent of soft-tissue infections and offers multiplanar capability, but it may not detect inflammation or necrosis as sensitively as MRI 1.
- Nuclear medicine studies, such as labeled leukocyte scans or sulfur colloid marrow scans, are useful in evaluating active infection, especially when orthopedic hardware is present 1.
Clinical Application
In clinical practice, the choice of imaging modality should be guided by the suspected location of the infection, patient factors (such as age and the presence of orthopedic hardware), and local resource availability. For instance, MRI with contrast is the modality of choice in the evaluation of osteomyelitis, as it provides detailed images of bone and soft tissue infections 1.
Additional Recommendations
- For suspected septic arthritis, joint aspiration is recommended, and ultrasound or fluoroscopy can be used to guide the procedure 1.
- In cases where abscess drainage is necessary, ultrasound or CT can be used to guide the procedure 1. By considering these factors and recommendations, clinicians can select the most appropriate imaging modality to evaluate for infection and guide effective treatment.
From the Research
Imaging Modalities for Infection Evaluation
The best imaging modality to evaluate for infection depends on the location and type of infection. Some of the commonly used imaging modalities include:
- Computed Tomography (CT) scans, which are accurate for identifying and treating intra-abdominal fluid collections and abscesses 2
- Ultrasound, which is preferred for identifying biliary or hepatic sepsis 2
- Magnetic Resonance Imaging (MRI), which can better characterize the skull base, intracranial involvement, and osteomyelitis in head and neck infections 3
- Positron Emission Tomography (PET) scans, which can detect metabolic perturbations or levels of expression of specific targets, but lack specificity for infection 4
Specific Imaging Modalities for Different Types of Infections
- For head and neck infections, contrast-enhanced CT is the standard imaging modality, while MRI is useful for characterizing the skull base, intracranial involvement, and osteomyelitis 3
- For pulmonary infections, CT scans are increasingly used to increase the sensitivity of radiologic diagnosis, especially when the radiograph is normal or findings are equivocal 5
- For intra-abdominal infections, CT scans are accurate for identifying and treating fluid collections and abscesses 2
Limitations and Future Directions
- Current imaging modalities lack specificity for infection, and there is a need for the development of pathogen-specific radiotracers 4
- New technologies, such as iodine-free contrast media and artificial intelligence algorithms, may improve CT image reconstruction and reduce the need for contrast media and radiation doses 6