ARRS 2022 Abstracts

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E2128. Thoracic Outlet Syndrome: Overview of Imaging Findings Across All Modalities
Authors
  1. Kevin Hoang; Cedars-Sinai Medical Center
  2. Meng Geng; Cedars-Sinai Medical Center
  3. Kavish Gupta; Cedars-Sinai Medical Center
Background
Thoracic outlet syndrome (TOS) is a group of syndromes resulting from compression of the brachial plexus and/or subclavian vessels at the thoracic outlet. Depending on the involved structures, TOS may present with a variety of symptoms ranging from paresthesia to total limb ischemia. TOS predominantly affects younger populations and is typically neurogenic in nature. Conservative management is available, though a high incidence of recurrence often makes surgical intervention necessary.

Educational Goals / Teaching Points
The purpose of this exhibit is to review key imaging findings associated with TOS across various imaging modalities, including MRI, CT, US, and angiography. Learners should be able to identify the preferred imaging modalities for evaluation of each subtype of TOS and make recommendations on further diagnostic work-up and referrals for management as necessary.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The preferred imaging modality for TOS varies based on the involved structures. Radiography is often completed first for evaluation of structural causes. For evaluation of vascular TOS (vTOS), ultrasound with Doppler is the initial diagnostic test of choice, followed by CT angiography/venography for equivocal cases. MRA/MRV has the highest sensitivity/specificity in difficult cases and limits radiation. Findings of enlarged collateral vessels, anatomic abnormalities, and dynamic vessel compromise/narrowing suggest vTOS but are not diagnostic. Thrombus or signs of vascular damage (fixed stenosis, aneurysm, pseudoaneurysm) must be present for a diagnosis of vTOS to be made. In neurogenic TOS, routine MRI of the neck and upper chest may again demonstrate causative anatomic abnormalities, as well as muscular atrophy and loss of normal fat planes. MRI of the brachial plexus may also demonstrate nerve compression with associated endoneurial fluid and edema. Across all modalities, dynamic images in neutral position and at 90-degee abduction must be obtained.

Conclusion
Though no gold standard test exists, imaging plays an important role in the diagnosis of TOS. Dynamic images must be obtained whenever TOS is suspected. Various findings may suggest vascular TOS, but thrombus or signs of vascular injury must be present for a diagnosis to be made.