Imaging for Neurogenic Thoracic Outlet Syndrome

Initial Imaging Approach

The American College of Radiology recommends MRI of the chest without IV contrast as the initial imaging modality for diagnosing neurogenic TOS, as it directly visualizes the brachial plexus and can demonstrate compression of neurovascular bundles in the costoclavicular, interscalene, and pectoralis minor spaces 1, 2
Plain chest radiography is used to identify osseous abnormalities, such as cervical ribs or first rib anomalies, which account for 36% of neurogenic TOS cases, serving as a screening tool before proceeding to advanced imaging 1

MRI without IV contrast is sufficient for neurogenic TOS diagnosis and should be performed after chest radiography, providing direct visualization of the brachial plexus and cervical spine, superior soft tissue characterization, and dynamic evaluation capability 1, 2
The MRI protocol must include specific sequences and positioning, such as high-resolution T1-weighted and T2-weighted sequences in sagittal and axial planes, to delineate the brachial plexus, muscular attachments, and compression sites 3

CT is limited by lack of resolution of neural structures, though it can show secondary indicators like space narrowing, and is primarily valuable for identifying bony abnormalities but cannot directly visualize the brachial plexus 1, 2
Arteriography and venography are unable to directly image neurologic structures and are not considered first-line tests for neurogenic TOS 1, 2

The American College of Radiology advises against relying on CT or ultrasound alone for neurogenic TOS, as these modalities lack adequate resolution of neural structures 1, 3
It is essential to evaluate for concomitant cervical spine pathology, which may mimic or exacerbate TOS symptoms, and to assess for severe cervical spondylosis, which can contribute to symptoms 3

MRI without IV contrast may be performed postoperatively to evaluate interval changes in the thoracic outlet and assess adequate decompression, with post-contrast imaging useful to assess soft tissues for inflammatory or neoplastic conditions 1