Utility of Acetazolamide-challenged CT Perfusion in Patients with High-grade Carotid Stenosis

Kim, Ho Sung; Kim, Sun Yong

Abstract

OBJECTIVE
To correlate quantitative cerebrovascular reserve calculated by acetazolamide - challenged CT perfusion with clinical symptoms in hemodynamically compromised patients with high-grade (>70%) carotid stenosis, who did not have evidence of embolic stroke.
MATERIALS AND METHODS
37 patients diagnosed as unilateral severe carotid stenosis and 10 age-matched normal controls underwent acetazolamide - challenged CT perfusion. For quantitative measurement, asymmetric index of cerebral blood flow, cerebral blood volume, and mean transit time were determined before and after acetazolamide challenge. Reactivity index was also calculated from asymmetric index of cerebral blood flow before and after acetazolamide challenge.
RESULTS
On visual analysis, all of 14 asymptomatic patients and 4 of 23 symptomatic patients showed bilateral symmetric cerebrovascular reserve on CT perfusion, and 19 symptomatic patients showed decreased cerebrovascular reserve ipsilateral to carotid stenosis. On quantitative analysis, the reactivity index was significantly different between the symptomatic and the asymptomatic groups (-24% vs -8% in external border zone) but the resting parameters were not. 11 patients with decreased cerebrovascular reserve who underwent carotid stenting showed improved clinical symptoms and quantitative cerebrovascular reserve on follow up CT perfusion.
CONCLUSION
Compared with resting hemodynamic parameters, quantitative cerebrovascular reserve calculated by CT perfusion is most significantly correlated with clinical symptoms in hemodynamically compromised patients with high-grade carotid stenosis.