Duplex ultrasound verified by angiography in patients with severe primary and restenosis of internal carotid artery

There are very limited data in the literature about the reliability of duplex ultrasound (DU) verified by angiography in patients with restenosis of the internal carotid artery (ICA) after carotid surgery compared with primary carotid artery stenosis patients. Our objective was to compare the reliability of DU verified by conventional angiography in the diagnosis of severe primary stenosis versus restenosis of ICA. One hundred thirty-four patients (238 arteries) were examined by both DU and angiography. Severe stenosis (>70%) was found in 47 primary stenotic arteries and in 70 restenotic arteries. Accuracy, specificity, sensitivity, positive predictive value (PPV), and negative predictive value were obtained for basic DU criteria after verification of ultrasound data by angiography. The best accuracy for detection of >70% stenosis by end diastolic velocity was found for the velocity of 70 cm/sec or more in both groups, but accuracy for the restenosis group was significantly higher (96.9% vs. 89.8%, p = 0.025). Additionally, specificity (p = 0.01) and PPV (p = 0.01) were significantly higher in the restenosis group. The best accuracy for detection of >70% stenosis by peak systolic velocity was found for the velocity of 220 cm/sec or more for restenoses and 200 cm/sec or more for primary stenoses. The accuracy of the ultrasound was significantly higher in the restenosis group (94.6% vs. 87%, p = 0.04), as were specificity (p = 0.01) and PPV (p = 0.02). The diagnosis of severe restenosis by DU is reliable and can be used for decision making regarding surgery or stenting without angiography. In patients with Doppler parameters pointing to borderline moderate/severe primary carotid stenosis and technically complicated cases, angiography in addition to sonography before surgery is recommended.