What is the recommended imaging study for thoracic outlet syndrome (TOS)?

From the Guidelines

For the evaluation of vascular Thoracic Outlet Syndrome (vTOS), chest CT with IV contrast is the preferred imaging study. This is based on the most recent evidence from the American College of Radiology, which highlights the advantages of contrast-enhanced CT in visualizing vascular structures and assessing vascular patency 1. The use of IV contrast allows for the evaluation of vascular compression and potential complications in the postintervention setting.

When considering imaging options, the following points are important:

• Chest CT without IV contrast may be used in the postintervention setting to evaluate interval changes in the thoracic outlet and assess adequate decompression 1.
• The acquisition of chest CT with IV contrast is typically performed with a contralubital antecubital injection of contrast material, providing enhanced visualization of vascular structures 1.
• Other imaging modalities, such as MRI or MRA, may be useful in evaluating the neurovascular structures and potential compression sites, but chest CT with IV contrast is preferred for vTOS due to its ability to assess vascular patency 1.

In clinical practice, it is essential to prioritize the imaging modality that provides the most accurate diagnosis and assessment of potential complications, which in this case is chest CT with IV contrast for vTOS 1.

From the Research

Imaging Studies for Thoracic Outlet Syndrome

The following imaging studies are used to assess thoracic outlet syndrome:

• Cervical plain radiography to assess for bone abnormalities and narrow the differential diagnosis 2
• Computed tomographic (CT) angiography or magnetic resonance (MR) imaging performed in association with postural maneuvers to analyze dynamically induced compression 2, 3
• B-mode and color duplex ultrasonography (US) as supplementary tools for assessment of vessel compression in association with postural maneuvers 2
• Contrast-enhanced magnetic resonance angiography (CE-MRA), short inversion time inversion recovery sampling perfection with application-optimized contrasts using different flip angle evolutions (T2-STIR-SPACE), and volumetric interpolated breath-hold examination (VIBE) sequences for evaluating neurovascular bundles 4

Diagnostic Value of Imaging Studies

The diagnostic value of imaging studies in thoracic outlet syndrome is as follows:

• MRI has a sensitivity of 41% and specificity of 33% in diagnosing TOS, with positive and negative predictive values of 89% and 4%, respectively 5
• MRI can demonstrate deviation or distortion of nerves or blood vessels, suggest the presence of radiographically invisible bands, and disclose other causes of thoracic outlet syndrome apart from ribs or bands 6
• A combination of computed tomography angiography and MRI (with postural maneuvers) can effectively demonstrate thoracic outlet syndrome abnormalities 3

Imaging Modalities

The following imaging modalities are used to evaluate thoracic outlet syndrome:

• Magnetic Resonance Imaging (MRI) to search for neurologic compression 2, 6, 5
• Computed Tomography (CT) angiography to analyze dynamically induced compression 2, 3
• Ultrasonography (US) to assess vessel compression in association with postural maneuvers 2
• Contrast-enhanced magnetic resonance angiography (CE-MRA) to evaluate neurovascular bundles 4