Is a magnetic resonance (MR) scan necessary for surgeons to evaluate osteomyelitis diagnosed on an X-ray (X-ray)?

From the Guidelines

Surgeons typically need an MRI in addition to X-rays when osteomyelitis is suspected or identified, as MRI provides crucial detailed anatomical information for surgical planning, including the extent of bone marrow edema, soft tissue involvement, abscess formation, and sinus tracts. While X-rays can show bone destruction and periosteal reaction in later stages of osteomyelitis, they lack sensitivity in early disease and provide limited soft tissue detail 1. According to the most recent study from 2022, MRI is generally considered preferable in detection of early manifestations of osteomyelitis, as well as infection of the surrounding soft tissues, because of the rapid progression of disease 1.

Key Points for Surgical Planning

• MRI offers superior evaluation of the full extent of infection, including bone marrow edema, soft tissue involvement, abscess formation, and sinus tracts.
• X-rays provide an overview of bone structure and alignment, but lack the detailed soft tissue and bone marrow assessment needed for precise surgical planning.
• The combination of X-rays and MRI is complementary, with X-rays providing initial anatomic evaluation and MRI offering detailed assessment of infection extent and surrounding tissue involvement.

Alternative Imaging Modalities

• In cases where MRI is contraindicated, CT scan with contrast or nuclear medicine studies may serve as alternatives 1.
• However, MRI remains the modality of choice for evaluating osseous infection in both adult and pediatric populations, due to its high sensitivity and specificity, as well as lack of ionizing radiation 1.

Clinical Considerations

• The choice of imaging modality should be guided by the clinical context, including the patient's symptoms, medical history, and potential contraindications to MRI or other imaging modalities.
• Surgeons should consider the potential benefits and limitations of each imaging modality when planning surgical intervention for osteomyelitis.

From the Research

Necessity of MR Scan for Evaluating Osteomyelitis

• The diagnosis of osteomyelitis can be challenging, and imaging modalities play a crucial role in its evaluation 2, 3, 4, 5, 6.
• Magnetic Resonance (MR) imaging has been shown to be highly sensitive and specific for the diagnosis of osteomyelitis, particularly in distinguishing bone-marrow processes from soft-tissue disease 2, 4, 5.
• A study published in 1988 found that MR imaging had a sensitivity of 92% and a specificity of 96% for the diagnosis of osteomyelitis, compared to bone scintigraphy which had a sensitivity of 82% and a specificity of 65% 2.
• Another study published in 2000 highlighted the importance of MR imaging in the diagnosis of chronic osteomyelitis, particularly in detecting and delineating areas of active infection 3.
• A more recent study published in 2023 found that MR imaging had significantly higher sensitivity and negative predictive value than radiography for the diagnosis of extremity osteomyelitis, with a sensitivity of 92% and a specificity of 96% 5.
• The use of MR imaging can provide valuable information for surgeons in evaluating osteomyelitis, particularly in cases where the diagnosis is uncertain or where there are multiple foci of infection 4, 6.

Comparison with Other Imaging Modalities

• Radiography is often the first-line imaging modality for musculoskeletal pathology, but it has limited sensitivity and specificity for the diagnosis of osteomyelitis 5.
• Computed Tomography (CT) can be used to evaluate bony alterations and guide percutaneous biopsy or drainage, but it has limited soft-tissue contrast compared to MR imaging 3.
• Bone scintigraphy has high sensitivity for the diagnosis of acute osteomyelitis, but it has limited specificity and can be affected by factors such as bone marrow processes and soft-tissue disease 2.

Clinical Implications

• The use of MR imaging can improve the diagnostic accuracy of osteomyelitis and provide valuable information for surgeons in evaluating the extent of infection and planning treatment 2, 4, 5.
• MR imaging can also help to distinguish between bone-marrow processes and soft-tissue disease, which can be challenging with other imaging modalities 2, 3.
• The results of MR imaging should be interpreted in conjunction with clinical and radiologic findings to ensure accurate diagnosis and treatment of osteomyelitis 3, 4, 6.