Stenosis and Pseudostenosis of the Upper Extremity Arteries in Large‐Vessel Vasculitis

OBJECTIVE: Pseudostenosis is a magnetic resonance angiography (MRA) artifact that mimics arterial stenosis. The study objective was to compare imaging and clinical aspects of stenosis and pseudostenosis in a cohort of large‐vessel vasculitis (LVV), including giant‐cell arteritis (GCA) and Takayasu's arteritis (TAK). METHODS: Patients with LVV and comparator conditions (healthy or vasculopathies) underwent MRA of the aortic arch vessels. The subclavian and axillary arteries were systematically assessed for presence of stenosis and pseudostenosis by two independent readers. Serial and delayed imaging and clinical assessments were used to confirm suspected pseudostenoses. Multivariable regression analyses were used to identify associations between angiographic pathology and clinical findings. RESULTS: One hundred eighty‐four MRA scans were analyzed from patients with GCA (n = 36), TAK (n = 47), and comparators (n = 25). Pseudostenoses were frequently observed (48 of 184 scans, 26%) in the distal subclavian artery only on the side of injection and were shorter in length compared with true stenoses (25 mm vs 78 mm, P < 0.01). There was no difference in prevalence of pseudostenosis by diagnosis (GCA = 33%, TAK = 23%, comparator = 20%, P = 0.44), disease activity status (P = 0.31), or treatment status (P = 1.00). Percent and length of true stenosis were independently associated with pulse and blood pressure abnormalities in the upper extremity. Adjusting for length and stenosis degree, absence of collateral arteries was associated with arm claudication (odds ratio = 2.37, P = 0.03). CONCLUSION: Although a pseudostenosis could be falsely interpreted as an arterial stenosis, radiographic and associated clinical features can help distinguish true disease from arterial susceptibility artifacts. In addition, the peripheral vascular examination can help to confirm a suspected true stenosis, as specific aspects of angiographic pathology are associated with vascular examination abnormalities in LVV.