Is an Magnetic Resonance Imaging (MRI) with or without contrast indicated to diagnose osteomyelitis in a patient?

From the Guidelines

For suspected osteomyelitis, an MRI with or without contrast is appropriate, as both are considered equivalent alternatives for providing the necessary clinical information to effectively manage the patient's care. The choice between the two may depend on specific patient factors, such as renal function or allergies to gadolinium-based contrast agents 1. In general, contrast-enhanced MRI can provide better differentiation between infected bone and surrounding soft tissue inflammation, improving diagnostic accuracy. However, in patients where contrast is contraindicated, non-contrast MRI remains a valuable diagnostic tool, albeit with potentially reduced sensitivity.

Some key considerations include:

• The use of contrast agents can help identify abscesses and improve detection of certain features of osteomyelitis or septic arthritis 1.
• In patients with severe renal impairment, contrast should be avoided due to the risk of nephrogenic systemic fibrosis.
• Non-contrast MRI can still detect bone marrow edema and anatomical changes, but may not distinguish as clearly between active infection and other conditions that cause bone marrow edema.
• The radiologist should be informed about the specific clinical suspicion of osteomyelitis to optimize the imaging protocol accordingly.

It's also important to note that the most recent guidelines suggest that MRI with or without contrast is appropriate for suspected osteomyelitis, and the choice between the two should be based on individual patient factors and clinical judgment 1.

From the Research

MRI for Osteomyelitis Diagnosis

• The use of MRI with or without contrast for diagnosing osteomyelitis has been studied in various research papers 2, 3, 4, 5, 6.
• A study from 2020 compared the use of ferumoxytol and gadolinium as contrast agents for MRI diagnosis of osteomyelitis, finding that both agents correlated with systemic markers of inflammation, but ferumoxytol-induced MRI contrast changes were more promising for diagnosing osteomyelitis 2.
• Another study from 2021 found that MRI with and without contrast media has a higher sensitivity for identifying areas of bone necrosis in later stages of osteomyelitis, and that staging based on major and minor risk factors can help stratify patients for surgical treatment 3.
• A 2000 study evaluated the need for additional MR sequences, including administration of Gd-DTPA, after inconspicuous Short-Tau Inversion-Recovery (STIR) sequence to exclude the diagnosis of osteomyelitis, finding that the combination of STIR and T1SE images shows a high sensitivity and specificity for osteomyelitis 4.
• A 2021 study found that diabetes and confluent signal on T1-weighted images were independent risk factors for pedal osteomyelitis, and that patients with these risk factors should be evaluated for osteomyelitis with recommendation for bone biopsy in appropriate clinical settings 5.
• A 2022 study evaluated the usefulness of new and established MRI signs of osteomyelitis in long bones in adults, finding that multiple foci of bone marrow signal abnormalities, an irregular contour of marrow abnormality, and central marrow hypoenhancement without abscess are common signs of osteomyelitis of long bones in adults 6.

Contrast Agents for MRI

• The use of contrast agents such as gadolinium and ferumoxytol has been studied in the context of MRI diagnosis of osteomyelitis 2, 4, 6.
• A study from 2020 found that ferumoxytol-induced MRI contrast changes were more promising for diagnosing osteomyelitis than gadolinium-induced changes 2.
• Another study from 2000 found that the administration of Gd-DTPA increased the specificity of MRI diagnosis of osteomyelitis, but that the combination of STIR and T1SE images was sufficient for diagnosis in most cases 4.
• A 2022 study found that central hypoenhancing regions of marrow without abscess formation were common in cases of osteomyelitis, even when gadolinium was given 6.

Imaging Sequences for MRI

• The use of different imaging sequences, such as STIR, T1-weighted, and T2-weighted sequences, has been studied in the context of MRI diagnosis of osteomyelitis 2, 4, 5, 6.
• A study from 2000 found that the combination of STIR and T1SE images shows a high sensitivity and specificity for osteomyelitis 4.
• A 2021 study found that confluent signal on T1-weighted images was an independent risk factor for pedal osteomyelitis 5.
• A 2022 study found that confluent low-signal intensity on T1-weighted images was not always present in cases of osteomyelitis, but that confluent high-signal intensity on T2-weighted images was always present 6.