Power Doppler Ultrasonography as a Screening Test in Asymptomatic Carotid Artery Stenosis

Abstract

We investigated the accuracy and efficacy of power Doppler ultrasonography (PDU) as a screening test in asymptomatic 60–99 % internal carotid artery (ICA) stenosis. 95 patients with internal carotid artery stenosis were examined with PDU prior to digital subtraction angiography (DSA). The results of PDU were compared with those of DSA as a reference standard. The average examination time of both carotid arteries using PDU was 3.25±1.25 minutes. The results of PDU and DSA showed a good correlation (r=0.79, p<0.001). PDU significantly underestimated ICA stenosis. The average difference between the results of PDU and DSA was −5 (95% CI: −8, −3). This underestimation was more marked at the level of 50–99 % angiographic stenosis. In determining 60–99% ICA stenosis, the sensitivity of PDU was 59% and its specificity was 97%. By taking into consideration PDU's underestimation, a PDU measurement of 45% was determined as the new threshold with high sensitivity which is suitable for purposes of screening. For this threshold, the sensitivity was found to be 95% and specificity 82%. The agreement between the observers in determining ICA stenosis by PDU was found to be fair to good (κ=0.48). PDU underestimates ICA stenosis, but this underestimation can be counterbalanced by taking a lower threshold. PDU is a rapid and easily performed method which has sufficient accuracy as a screening test in determining ICA stenosis.