Application of dual source 64-slice CT angiography in evaluating internal vertebral artery stenosis

Objective To evaluate the diagnostic accuracy of dual source 64-slice computer tomographyic angiography(CTA) for internal vertebral artery stenosis.Methods Sixty-one posterior circulation stroke or TIA patients with interpretable CTA and digital subtraction angiography(DSA) of the vertebral arteries were selected.In CTA,the grade of stenosis was determined using axial source,maximum intensity projection(MIP),multi-plane reconstruction(MPR) as well as volume rendering(VR) images.The images were blindly analyzed by two neuroradiologists using the North American Symptomatic Carotid Endarterectomy trial(NASCET) criteria separately.Results CTA agreed with DSA categorization of a stenosis in 100 of the 122 arteries.When 70% stenosis was used as the cut-off value,the sensitivity,specificity,negative predictive value and the positive predicting value were 96.4%,96.8%,98.9% and 90.0%,respectively.When 50% stenosis was used as the cut-off value,the sensitivity,specificity,negative predictive value and the positive predicting value were 97.9%,89.2%,98.5% and 85.5%,respectively.Degree of artery stenosis on CTA closely correlated with that on DSA(r=0.98,P0.01).Conclusion An excellent correlation and high accuracy were demonstrated between CTA and DSA on degree of stenosis,thus CTA appears to be an excellent screening test for vertebral artery stenosis.