Duplex scanning and CT angiography in the diagnosis of carotid artery occlusion: a prospective study

Objectives: Differentiating total occlusion from tight stenosis of the internal carotid artery is crucial with regard to treatment and prognosis. At our institution, the diagnosis of carotid stenosis is based on duplex scanning. In cases of occlusion, duplex is not reliable, and angiography is performed, thereby increasing morbidity. We tried to determine whether a combination od duplex scanning and CT angiography (CTA) can replace angiography in the diagnosis of carotid occlusion. Design: Prospective study. Materials and methods: From 1995 to 1997, 148 patients were diagnosed as having carotid occlusion by duplex scanning. CTA was performed on all patients. Forty-four patients underwent angiography and 10 patients were surgically explored. Both procedures were considered "gold standard" for the diagnosis of occlusion. Results: Arteries found to be occluded by both CTA and duplex scan were confirmed as occluded by angiography or operation in 95% of the cases (42/44). Arteries found to be occluded by duplex but patent by CTA were confirmed as patent in 100% of cases (10/10). CTA has a significantly higher positive predicting value for diagnosing occlusion than duplex scan (95% vs. 77%, p value <0.01). Conclusions: Combination of duplex scanning and CTA is safe and accurate in the diagnosis of carotid occlusion and can replace angiography in most cases, thereby reducing morbidity.