Several correlations between PSV and the degree of stenosis measured by X-ray angiography were published [10] and

a consensus for threshold values based on a meta-analysis was published [4]. However all correlations between PSV and angiography showed a considerable scatter. Therefore the NASCET group [2] and recently the AHA did not recommend carotid surgery in symptomatic patients based on duplex sonography alone [8]. In Germany, as in other European countries the local diameter narrowing (ESCT method) was popular whereas in the US the distal diameter of the internal carotid artery (ICA) was taken as denominator (distal diameter narrowing, NASCET method). http://www.selleckchem.com/products/PLX-4032.html The ESCT method results in higher degrees of stenosis especially in the range of up to 70% stenosis [11]. This opened the possibility of misuse by measuring following the ESCT method and recommending carotid surgery following the NASCET criterion of 70%.

In consequence new intersociety guidelines were published in Germany [1] very similar to the first ones [15], but using the NASCET method as the morphologic correlate. In addition the role of color coded imaging for detecting Target Selective Inhibitor Library manufacturer low degree disease and total occlusion was added, as well as PSV values. Recently a similar consensus was reached by the Neurosonology Research Group (NSRG) of the WFN [10]. Both of these guidelines emphasize the difference between main or primary and additional criteria. They are listed in Table 1. This article shall outline the background

of grading a stenosis and especially focus on the weighting of these ultrasonic criteria as main and secondary. A stenosis can be graded following its morphologic or hemodynamic effect. The morphologic Methisazone aspect is measured in mm or as percent diameter reduction. Additional features can be described as precise location or shape of the plaque, regular or irregular. The hemodynamic effect can be measured as local flow velocity at the level of a plaque or stenosis [13], pressure drop or reduced flow volume. Doppler ultrasound in its clinical application cannot measure the two last parameters directly, but make estimations by measuring prestenotic side to side differences, the appearance of collateral flow, the poststenotic pulsatility and velocity of flow and flow disturbances [6]. Both the morphologic parameters and the hemodynamic parameters can be translated to each other, i.e. “a hemodynamic relevant stenosis corresponds to a ≥70% stenosis (NASCET)”, or “in a 80% stenosis collateral flow via the circle of Willis is highly probable”. In general the final diagnosis will be expressed in % diameter reduction, as it is the tradition with angiography. In mild degrees of stenosis duplex sonography describes both the morphology and local hemodynamic as well. With increasing severity a precise morphologic description is more difficult due to calcium shadowing and reverberation. Hemodynamic parameters are however more useful.