Diagnostic Approach for Aberrant Right Subclavian Artery

Primary Imaging Modality

The American College of Radiology recommends CT angiography (CTA) as the test of choice for diagnosing an aberrant right subclavian artery (ARSA) coursing posterior to the esophagus, due to its excellent anatomic detail of vascular structures and their relationship to surrounding tissues 1, 2
CTA offers superior visualization of the aberrant vessel, its origin from the aortic arch, and its retroesophageal course, allowing for accurate assessment of the degree of stenosis and compression of surrounding structures 1
Volume-rendered 3D reconstructions from CTA provide optimal simultaneous analysis of both vascular and bony structures, which is crucial for evaluating compression of adjacent structures 1

MRI/MRA is an excellent alternative to CTA when radiation exposure is a concern, detailed soft tissue evaluation is needed, or the patient has contraindications to iodinated contrast 1, 3, 4
MRA with contrast provides comprehensive assessment of both soft tissues and vascular structures, making it particularly valuable for evaluating compression of adjacent structures 1

For CTA, both axial images and multiplanar reformations should be evaluated to assess the severity of stenosis, and studies should be evaluated on dedicated vascular workstations for optimal assessment 1
For MRA, imaging should be performed in both neutral and arms-abducted positions to assess for dynamic compression, and T1-weighted imaging in sagittal and axial planes helps demonstrate causative lesions 1

CTA has been shown to have excellent correlation with operative findings in arterial compression syndromes, and can accurately identify the presence of Kommerell's diverticulum, which occurs in 20-60% of patients with ARSA 1, 5

The European Heart Journal recommends measurement of key diameters, including the diverticulum orifice and the combined diameter of the diverticulum and adjacent descending thoracic aorta, for management decisions 2, 5
Intervention is recommended when the Kommerell's diverticulum orifice is >3.0 cm, the combined diameter of the diverticulum and adjacent descending aorta is >5.0 cm, or the patient is symptomatic with dysphagia, respiratory symptoms, or recurrent laryngeal nerve palsy 2, 5