Thoracic outlet syndrome (TOS) refers to a variety of conditions caused by compression of neurovascular structures as they traverse the thoracic outlet. Arterial TOS is considered the rarest form. 

The diagnosis of TOS is usually made clinically. Imaging is helpful in identifying the exact location and cause of compression. CT-angiography is effective in demonstrating arterial compression if performed in neutral position and with raised arms. The contrast medium should be injected from the opposite side.