Is contrast necessary on MRI to evaluate osteomyelitis?

From the Guidelines

Contrast is not always necessary on MRI to evaluate osteomyelitis, as fluid-sensitive sequences alone may be sufficient for diagnosis, with sensitivity reportedly 82% to 100% and specificity 75% to 96% 1.

Key Points

• MRI sensitivity and specificity: Fluid-sensitive sequences have high sensitivity and specificity for diagnosing osteomyelitis, with values ranging from 82% to 100% and 75% to 96%, respectively 1.
• Use of contrast: While contrast is not always necessary, it can improve detection of abscesses and provide additional information on the extent of soft-tissue involvement 1.
• Specific scenarios: In certain scenarios, such as differentiating osteomyelitis from Ewing sarcoma or evaluating chronic osteomyelitis, contrast may be more useful 1.
• Alternative imaging modalities: Other imaging modalities, such as CT, ultrasound, and nuclear scans, may also be useful in evaluating osteomyelitis, particularly in cases where MRI is contraindicated or not available 1.

Important Considerations

• Clinical context: The decision to use contrast on MRI for osteomyelitis evaluation should be made on a case-by-case basis, taking into account the clinical context and specific patient factors 1.
• Radiologist expertise: The expertise of the radiologist interpreting the MRI is also crucial in determining the need for contrast, as they can assess the quality of the images and decide whether additional information is needed 1.

From the Research

Evaluation of Osteomyelitis using MRI

• The use of contrast-enhanced MRI for evaluating osteomyelitis has been studied in several research papers 2, 3, 4, 5, 6.
• According to a study published in 1992, MRI has proven to be as sensitive as bone scintigraphy in the early detection of osteomyelitis, and with its superior spatial resolution, MR is often more specific than planar scintigraphy in differentiating bone from soft-tissue infection 2.
• A study published in 2009 found that the use of fat-suppressed contrast-enhanced MRI increases reader confidence in the diagnosis of osteomyelitis and its complications in children, although it does not increase the sensitivity or specificity of the diagnosis 3.
• A systematic review published in 2022 found that MRI with gadolinium-based contrast has a sensitivity of 89% and specificity of 79% for diagnosing osteomyelitis in the appendicular skeleton, while MRI without gadolinium-based contrast has a sensitivity of 92% and specificity of 89% 4.
• Another study published in 2000 found that the combination of STIR and T1SE images shows a high sensitivity and specificity for osteomyelitis, thus obviating the need for any additional examinations, including contrast-enhanced MRI 5.
• In terms of spinal osteomyelitis, a study published in 2000 found that SPECT Ga-67 is as accurate as SPECT bone/Ga-67 and as sensitive as MRI, and can be used as a reliable alternative when MRI cannot be performed 6.

Use of Contrast-Enhanced MRI

• The evidence suggests that contrast-enhanced MRI may not be necessary for the diagnosis of osteomyelitis in all cases 3, 4, 5.
• However, contrast-enhanced MRI may be helpful in certain situations, such as in the diagnosis of spinal osteomyelitis or in cases where the diagnosis is uncertain 2, 6.
• The decision to use contrast-enhanced MRI should be made on a case-by-case basis, taking into account the individual patient's circumstances and the specific clinical question being addressed 3, 4.