Rate of arterial occlusion in patients with acute ischemic stroke

Objective: Computed tomographic angiography (CTA) was invented more than 20 years ago, but only gained acceptance recently, thanks to advancements in the computer technology. It can demonstrate areas of arterial stenosis or occlusion with accuracy nearly that of digital subtraction angiography (DSA). It is also able to clearly illustrate calcification, which is more difficult to define on magnetic resonance angiography and is not clearly depicted on DSA. Methods: Our retrospective study attempted to clarify the rate of occlusion or stenosis in the patients with acute ischemic stroke. Results: Over the period of 7 months, 93 consecutive patients were admitted with acute ischemic stroke. Fifty-six patients underwent CTA and were included in this study. Most of the patients were admitted after 6 hours following onset of symptoms. There were 28 men and 28 women, and 80.4% of the cohort was of African-American origin. The majority of strokes were attributed to small-vessel disease (25/56). The rest of the cases were deemed secondary to atheroembolism (15/56), cardioembolism (9/56) or of unclear etiology (7/56). In 24 (42.9%) patients, CTA failed to reveal any abnormalities of the cerebrovascular tree. CTA demonstrated arterial occlusion in ten (17.9%) patients and stenosis of extracranial or intracranial arteries on the symptomatic side in 22 (39.2%) patients. There was very good correlation between CTA and ultrasound techniques (carotid duplex and transcranial Doppler). CTA was superior in demonstrating distal intracranial stenosis. Conclusion: Overall, CTA is an extremely valuable and fast way to emergently evaluate the cerebrovascular anatomy, making it very useful for pre-thrombolysis evaluation of patients with ischemic stroke.