From the Guidelines
A CT scan with contrast is the preferred imaging modality for investigating a suspected sacral ulcer that might result in osteomyelitis, as it allows for better visualization of soft tissue infection and bone involvement. The use of contrast enhancement in CT scans is crucial for differentiating between infected and non-infected tissues, as infected areas often show increased enhancement due to inflammation and increased blood flow 1. According to the American College of Radiology (ACR) appropriateness criteria, CT with IV contrast is rated as a 7, indicating that it is usually appropriate for suspected osteomyelitis, especially when MRI is contraindicated 1.
The advantages of using CT with contrast include:
- Better visualization of soft tissue infection, abscess formation, and the extent of bone involvement
- Ability to differentiate between infected and non-infected tissues
- Helps delineate the spread pathway of osteomyelitis and any associated complications like sinus tracts or abscesses that require drainage
However, if the patient has contraindications to contrast, such as severe renal impairment or allergy to iodinated contrast, an MRI would be a better alternative than a non-contrast CT, as MRI provides superior soft tissue resolution even without contrast agents 1. The ACR appropriateness criteria update in 2022 recommends MRI with or without IV contrast as the next imaging study for suspected osteomyelitis following normal radiographs or with findings suggestive of osteomyelitis 1.
In terms of radiation exposure, CT scans with contrast have a variable relative radiation level (RRL), while MRI has a lower RRL 1. Ultimately, the choice of imaging modality depends on the individual patient's circumstances and the clinical suspicion of osteomyelitis. CT with contrast is the recommended initial imaging modality for suspected sacral ulcer-related osteomyelitis, unless contraindicated.
From the Research
Imaging Options for Sacral Ulcer Investigation
To investigate a suspected sacral ulcer that might result in osteomyelitis, imaging options such as CT scans with or without contrast can be considered. However, the provided evidence suggests that:
- Magnetic resonance imaging (MRI) with and without contrast media has a higher sensitivity for identifying areas of bone necrosis in later stages of osteomyelitis 2.
- MRI can be a useful tool for identifying factors such as osteomyelitis, fluid collections, abscesses, and sinus tracts in the perioperative period 3.
Use of Contrast in CT Scans
Regarding the use of contrast in CT scans:
- Iodinated contrast is administered to define anatomical structures and detect pathologies, and its use can be optimized based on various factors such as patient weight, cardiac output, and technical characteristics of the scan 4.
- However, there is no direct evidence in the provided studies to support the use of CT scans with or without contrast as the primary imaging modality for investigating sacral ulcers that might result in osteomyelitis.
Diagnosis and Management of Osteomyelitis
In terms of diagnosing and managing osteomyelitis:
- Osteomyelitis is usually clinically diagnosed with support from imaging and laboratory findings, and bone biopsy and microbial cultures offer definitive diagnosis 2.
- The presence of osteomyelitis in stage-4 pressure ulcers does not necessarily lead to higher complication rates following flap coverage, and there is no evidence that bone biopsy and preoperative treatment of osteomyelitis have any benefit before flap coverage 5.
- The treatment of osteomyelitis in patients with stage IV sacral pressure ulcers is controversial, and antibiotic therapy may not be beneficial without concomitant surgical debridement and wound coverage 6.