Multimodality Imaging of Thoracic Outlet Syndrome: Etiological and Anatomical Correlates

Thoracic outlet syndrome (TOS) is a rare neurovascular compression disorder involving the brachial plexus and/or subclavian vessels at the cervicothoracobrachial junction. Clinical presentation is often nonspecific and may overlap with peripheral neuropathies, cervical spine disorders, and musculoskeletal conditions, making diagnosis challenging. Although clinical evaluation remains central to diagnosis, imaging plays a complementary role in supporting the diagnosis of TOS by identifying the affected neurovascular structures, localizing the site of compression, and elucidating the underlying anatomical or pathological causes. Moreover, imaging is essential for excluding alternative diagnoses, including thoracic malignancies and inflammatory or degenerative vascular diseases that may mimic TOS. This review provides a comprehensive overview of the radiological anatomy of the thoracic outlet, the etiological factors contributing to neurovascular compression, and the strengths and limitations of current imaging modalities used in the evaluation of TOS.