For evaluation of patients with nTOS, definition of the brachial plexus and cervical spine and dynamic evaluation of neurovascular bundles in the costoclavicular, interscalene, and pectoralis minor spaces are required. Noncontrast MRI can be sufficient to diagnose nTOS. In one study, for patients with nTOS, the neurovascular bundle was most commonly compressed in the costoclavicular space, mostly secondary to position, and very rarely compressed in the pectoralis minor space [16]. The cause of TOS was congenital bone variations in 36%, congenital fibromuscular anomalies in 11%, and positional in 53%. In 5%, there was unilateral brachial plexitis in addition to compression of the neurovascular bundle. Severe cervical spondylosis was noted in 14%, contributing to TOS symptoms [16]. MRI without IV contrast may also be performed in the postintervention setting to evaluate interval changes in the thoracic outlet and assess adequate decompression. Postcontrast imaging may additionally be useful to assess the soft tissues for inflammatory or neoplastic conditions. MRA Chest Contrast-enhanced 3-D MRA techniques do not provide evaluation of the neurologic structures. If there are overlapping symptoms, review of the other Variants in this document may help with protocol optimization. MRV Chest Contrast-enhanced 3-D MRV techniques do not provide adequate evaluation of the neurologic structures. This procedure is therefore not considered a first-line test for nTOS pre- or postoperatively. Radiography Chest Chest radiography is frequently used as an initial imaging modality in suspected TOS. Osseous abnormalities associated with TOS are frequently easily diagnosed by chest radiographs. These include first rib anomalies [20], cervical ribs [23], congenital osseous malformations [24,25], and focal bone lesions [26].
Thoracic Outlet Syndrome. For evaluation of patients with nTOS, definition of the brachial plexus and cervical spine and dynamic evaluation of neurovascular bundles in the costoclavicular, interscalene, and pectoralis minor spaces are required. Noncontrast MRI can be sufficient to diagnose nTOS. In one study, for patients with nTOS, the neurovascular bundle was most commonly compressed in the costoclavicular space, mostly secondary to position, and very rarely compressed in the pectoralis minor space [16]. The cause of TOS was congenital bone variations in 36%, congenital fibromuscular anomalies in 11%, and positional in 53%. In 5%, there was unilateral brachial plexitis in addition to compression of the neurovascular bundle. Severe cervical spondylosis was noted in 14%, contributing to TOS symptoms [16]. MRI without IV contrast may also be performed in the postintervention setting to evaluate interval changes in the thoracic outlet and assess adequate decompression. Postcontrast imaging may additionally be useful to assess the soft tissues for inflammatory or neoplastic conditions. MRA Chest Contrast-enhanced 3-D MRA techniques do not provide evaluation of the neurologic structures. If there are overlapping symptoms, review of the other Variants in this document may help with protocol optimization. MRV Chest Contrast-enhanced 3-D MRV techniques do not provide adequate evaluation of the neurologic structures. This procedure is therefore not considered a first-line test for nTOS pre- or postoperatively. Radiography Chest Chest radiography is frequently used as an initial imaging modality in suspected TOS. Osseous abnormalities associated with TOS are frequently easily diagnosed by chest radiographs. These include first rib anomalies [20], cervical ribs [23], congenital osseous malformations [24,25], and focal bone lesions [26].