The patients’ selection for surgical or endovascular intervention

is based on the degree of carotid stenosis, therefore an accurate assessment is required by means of non-invasive imaging and in some cases by catheter-based angiography. Several methods can be used during catheter-based angiography for stenosis measurement, but the most frequently used one is the NASCET (North American Symptomatic Carotid Endarterectomy Trial) [13], which define the degree of stenosis by measuring the minimal residual lumen at the level of the stenosis, then selleck products comparing it with the diameter of the more distal ICA, where the arterial walls become parallel. The diameter of the artery cannot be assessed directly by carotid duplex ultrasound. This method uses blood selleck screening library flow velocity to indicate the severity of stenosis. Duplex ultrasound may be insensitive to distinguish high-grade stenosis from complete occlusion [14]. The severity of stenosis measured by ultrasound can be categorized into 2 groups: 50–69% stenosis when flow velocity exceeds the normal value due to plaque formation, and 70–99% stenosis in case of more severe atherosclerotic alterations. In case of 50–69% stenosis the peak systolic velocity is in range of 125–230 cm/s and a plaque can be seen in the ultrasound picture. The ratio of peak systolic

velocities of internal to common carotid artery is between 2 and 4, while the end-diastolic velocity of ICA

reaches 40–100 cm/s. In case of >70% stenosis the peak systolic velocity exceeds 230 cm/s in ICA, the ratio of this value of internal to common carotid artery is above 4 and end-diastolic velocity accelerates above 100 cm/s in ICA [15]. The velocities of 70% and less severe stenosis overlap, which results in difficulties in the degree Tacrolimus (FK506) grading and which therefore indicates the use of other vascular imaging methods as well. Several factors can reduce the accuracy of ultrasound measurements, like obesity, vascular tortuosity, high carotid bifurcation or in situ carotid stents and it is also influenced by operator expertise. Because of the some diagnostic uncertainty new efforts tend to be invested to improve the accuracy of these measurements. The multi-parametric German “DEGUM ultrasound criteria”, which contained Doppler and imaging criteria combination, have been revised and transferred to NASCET measurement. The criteria are categorized into main and additional groups, in combination if which the accuracy of carotid stenosis grading by ultrasonography can be improved [16]. In 2011 a new guideline was published by ASA/ACCF/AHA/AANN/AANS/ACR/ASNR/CNS/SAIP/SCAI/SIR/SNIS/SVM/SVS [4] which specifies the principles of the management of patients with symptomatic or asymptomatic carotid and vertebral artery disease. The importance of non-invasive imaging methods in the diagnostic routine is evident.