Validity of Ultrasound for the Diagnosis of Arterial Thoracic Outlet Syndrome.

Objective: Thoracic outlet syndrome (TOS) is a rare disorder mostly seen in younger individuals. Although patient wellbeing is relevantly impaired, it often takes a long time before the diagnosis is made. Digital subtraction angiography (DSA) is routinely used despite its radiation exposure, which is a major concern in this young patient population. Moreover, DSA offers limited opportunities for functional assessment. By contrast, ultrasonography is widely accessible without causing radiation exposure and allows for flexible functional assessment. The main goal of the study was to investigate whether ultrasound (US) was a viable alternative to DSA in diagnosing arterial TOS (aTOS). Methods: Patients, referred to a tertiary centre for evaluation of suspected TOS, were recruited into the study. DSA was routinely performed with the patient's arms both in the raised (abducted) and neutral (adducted) position. Two vascular surgeons and two radiologists assessed the resulting images for the presence of aTOS. Additionally, two examiners performed US according to a standardised protocol. The reference for presence of aTOS was the DSA based interdisciplinary vascular conference consensus. Inter-rater agreement and latent class analysis (LCA) were performed between assessors and diagnostic methods. Results: Fifty one consecutive patients (two thirds female) aged 39.3 ± 13.0 years were included within 11 months. US agreement was excellent at 0.94 (0.841-0.980), DSA agreement for vascular surgeons was good at 0.779 (0.479-1.000), whereas it was moderate at 0.546 (0.046-1.000) for radiologists. Results suggest that DSA is untenable as the gold standard for aTOS diagnosis. In LCA, US was shown to be a reliable diagnostic tool for the detection of aTOS. Conclusion: US examination is a valid test for the detection of haemodynamically relevant compression of arteries in the diagnostic work up of aTOS using a standardised protocol. The role of DSA as the gold standard should be reviewed and needs to be reconsidered.