What is the yield of computed tomography (CT) for ruling out osteomyelitis?

From the Guidelines

Computed tomography (CT) has limited utility for ruling out osteomyelitis, with a yield that is generally lower compared to other imaging modalities like MRI or nuclear medicine studies. The yield of CT for ruling out osteomyelitis is influenced by its sensitivity and specificity, which are approximately 65-75% and 75-83%, respectively 1. CT is most useful for evaluating complex anatomical areas or assessing complications such as sequestra or abscesses, but it has limitations in detecting early bone marrow changes. Some of the key points to consider when evaluating the yield of CT for osteomyelitis include:

• CT provides excellent bone detail and can detect cortical destruction, sequestration, and periosteal reaction associated with osteomyelitis 1.
• MRI is generally superior for diagnosing osteomyelitis with higher sensitivity (90-95%) and better soft tissue contrast 1.
• Nuclear medicine studies like bone scans or FDG-PET may also be more sensitive than CT, particularly for early infection 1.
• CT may be considered when MRI is contraindicated or unavailable, but clinicians should be aware that a negative CT scan does not definitively exclude osteomyelitis, especially in early stages of infection 1. Given the most recent evidence from 2022, the use of CT for ruling out osteomyelitis should be approached with caution, and alternative imaging modalities should be considered when possible 1.

From the Research

Yield of CT for Ruling Out Osteomyelitis

• The yield of computed tomography (CT) for ruling out osteomyelitis is relatively low compared to other imaging modalities such as MRI, PET, and SPECT 2.
• A systematic review of imaging tests for osteomyelitis found that CT had a sensitivity of 69.7% and specificity of 90.2% 2.
• Another study compared the diagnostic accuracy of different imaging techniques in pediatric acute hematogenous osteomyelitis and found that CT had a sensitivity of 67% and specificity of 50% 3.
• CT may be useful in certain situations, such as evaluating osteomyelitis of the sterno-clavicular junction or hidden areas in the pelvic bones 4.
• However, other imaging modalities such as MRI and bone scintigraphy may be more accurate and preferred for diagnosing osteomyelitis 2, 3, 4.

Comparison with Other Imaging Modalities

• MRI had a higher diagnostic accuracy than CT, with a sensitivity of 95.6% and specificity of 80.7% 2.
• PET and SPECT also had higher diagnostic accuracy than CT, with sensitivities of 85.1% and 95.1%, and specificities of 92.8% and 82.0%, respectively 2.
• Bone scintigraphy had a sensitivity of 83.6% and specificity of 70.6%, which was also higher than CT 2.
• Ultrasound had a sensitivity of 55% and specificity of 47%, which was lower than CT 3.

Clinical Implications

• The choice of imaging modality for osteomyelitis should be based on the specific clinical scenario and the availability of imaging modalities 4.
• CT may be useful in certain situations, but other imaging modalities such as MRI and bone scintigraphy may be more accurate and preferred for diagnosing osteomyelitis 2, 3, 4.
• Further studies are needed to determine the optimal imaging algorithm for osteomyelitis and to compare the diagnostic accuracy of different imaging modalities in different clinical scenarios 2, 4.