What is the best imaging modality for suspected tendon (tendinous) or ligament injury to the ankle?

From the Guidelines

Magnetic Resonance Imaging (MRI) is the best imaging modality for suspected tendon or ligament injury to the ankle. This recommendation is based on the most recent and highest quality study available, which emphasizes the importance of MRI in assessing ligamentous injury and stability, particularly in athletes 1. MRI provides excellent soft tissue contrast, allowing for detailed visualization of ligaments, tendons, and surrounding structures, making it superior to other imaging techniques for these specific injuries.

When ordering an MRI for ankle injuries, a dedicated ankle protocol should be requested, preferably without contrast unless there is concern for infection or tumor. Patients should remove all metal objects before the scan, which typically takes 30-45 minutes to complete. While X-rays are often performed first to rule out fractures, they cannot adequately visualize soft tissue structures. Ultrasound can be useful for certain superficial tendons like the Achilles but lacks the comprehensive evaluation that MRI provides. CT scans excel at bone detail but offer limited soft tissue contrast.

Some key points to consider when evaluating ankle injuries include:

• The importance of delayed physical examination in diagnosing ligamentous injuries, with a sensitivity of 84% and specificity of 96% when performed 4-5 days post-injury 1.
• The role of ultrasound in evaluating soft-tissue abnormalities, including tendon and ligament tears, although its results are more dependent on operator skill and expertise 1.
• The use of radiography as the initial imaging study to rule out fractures, with a sensitivity of 92-99% for detecting ankle fractures using the Ottawa Ankle Rules (OAR) criteria 1.
• The potential for MRI to detect subtle abnormalities such as partial tears, tendinosis, ligament sprains, and associated bone marrow edema, allowing for accurate diagnosis and appropriate treatment planning for ankle tendon and ligament injuries 1.

Overall, MRI's superiority in evaluating ankle tendon and ligament injuries stems from its ability to provide comprehensive and detailed visualization of soft tissue structures, making it the preferred imaging modality for suspected tendon or ligament injury to the ankle.

From the Research

Imaging Modalities for Ankle Injuries

The best imaging modality for suspected tendon/ligament injury to the ankle is a topic of discussion among radiologists and medical professionals.

• Magnetic Resonance Imaging (MRI) is considered the imaging modality of choice for diagnosing ligament pathologies due to its multiplanar capability and high soft tissue contrast 2, 3.
• MRI is invaluable for assessing (partial) ruptures and evaluating accompanying injuries, and it provides detailed information on the anatomy and orientation of ankle ligaments 3.
• Ultrasound is also a useful tool for assessing ligaments and tendons, and it is recommended over MRI for diagnosis and monitoring of Achilles tendon ruptures 4.
• Three-dimensional (3D) MRI pulse sequences with isotropic voxel dimensions can achieve higher spatial resolution and similar contrast resolutions, making them suitable for visualizing oblique and curved structures around the ankle 5.

Comparison of Imaging Modalities

• A systematic review of 56 studies found that ultrasound and MRI were the most commonly used imaging modalities for diagnosing and monitoring Achilles tendon ruptures, with sensitivity ranging from 79.6 to 100% and specificity ranging from 0 to 100% 4.
• The review also found that MRI examination was generally performed with 1.5Tesla (T) MRI, with a strong trend for higher T strength in more recent studies 4.
• A study comparing 2D and 3D MRI found that 3D MRI provided higher spatial resolution and similar contrast resolutions, making it suitable for visualizing ankle structures 5.

Clinical Applications

• Imaging modalities, particularly ultrasound and MRI, play an adjunct role in the diagnosis and monitoring of ankle injuries, and they can provide additional clinical information to support treatment planning 3, 4.
• Clinical efficiency gains can be achieved by replacing two or three 2D FSE/TSE sequences within an ankle protocol with a single isotropic 3D FSE/TSE pulse sequence 5.