Objectives: CT angiography (CTA) is frequently employed in current clinical practice to evaluate the extent of cerebrovascular disease in patients with DU 50% extracranial ICA stenosis. We studied a) the prevalence of additional clinically significant intracranial or proximal arch occlusive disease not detected by DU, and b) whether such CTA findings predict progression in DU ICA stenosis category. Methods: From 2005 to 2010, 111 consecutive patients were studied retrospectively. 81 were asymptomatic and 30 symptomatic (TIA, stroke, AF). Kappa agreement between DU stenosis category and CTA was determined. Findings on CTA considered significant were 50% intracranial ICA stenosis, proximal CCA stenosis, intracranial aneurysm, vertebral stenosis or occlusion, 50% subclavian stenosis and diffuse atherosclerosis of the aortic arch. Progression of DU ICA stenosis from 50-79% to 80-99% was determined in relation to CTA findings. Results: Patient demographics were similar between asymptomatic and symptomatic patients Table 1. DU and CTA were performed within 6 months in 95% of cases. Agreement between DU and CTA was 0.9 (Kappa). 19% (21/111) of patients had CTA findings not detected by DU, of which 17 (21%) were in asymptomatic and 4 (13%) in symptomatic patients (p 0.60, NS) Table 2. Median follow up was 3.2 years. Progression from 50-79% to 8099% was detected in 4 (19%) and in 13 (14.4%) patients with and without additional CTA findings respectively (NS). Conclusions: For patients harboring 50% carotid bifurcation ICA stenosis by DU, CTA provides minimal information of clinical use. Progression of stenosis is unrelated to the presence of remote atherosclerotic plaque burden as detected on CTA. These findings suggests that CTA is over utilized in clinical practice and that DU performed in an ICAVL accredited lab is sufficient for planning carotid intervention if necessary.