Accuracy of computed tomographic angiography compared to digital subtraction angiography in the diagnosis of intracranial stenosis and its impact on clinical decision-making.

BACKGROUND: Few studies to date have examined the accuracy of computed tomographic angiography (CTA) compared to digital subtraction angiography (DSA) in diagnosing intracranial stenosis. The purpose of this study was to compare CTA to DSA in diagnosing intracranial stenosis and to explore the impact of the addition of DSA on the management of stroke patients.
METHODS: We retrospectively reviewed all ischemic stroke or patients with transient ischemic attack who underwent CTA and DSA within 30 days of each other at our institution between January 2008 and July 2011. For each study, 2 blinded observers rated the degree of stenosis of 11 intracranial vessels. Disagreements were adjudicated by a third blinded observer. Sensitivity, specificity, negative predictive value, and receiver operating characteristic curves were determined using DSA as the criterion standard. All patient charts were reviewed to determine if the addition of DSA to CTA impacted clinical management.
RESULTS: Six hundred twenty-seven arterial segments were reviewed. The sensitivity of CTA to diagnose stenosis >50% was 96.6% (95% confidence interval [CI] 88.1-99.6), specificity 99.4% (95% CI 98.1-99.9), and negative predictive value 99.6% (95% CI 98.4-99.9). The intraclass correlation between CTA and DSA measurements was 0.96 (95% CI 0.95-0.97). Five of 57 patients underwent intracranial stenting procedures during the study period. All 5 lesions were correctly characterized as having >70% stenosis on CTA. Of the remaining 52 patients, none had clinical management change based on DSA findings.
CONCLUSIONS: CTA has a high sensitivity and specificity compared to DSA to diagnose intracranial stenosis. The addition of DSA to CTA may not affect clinical management in most patients with suspected stenosis.