Prediction of angiographic carotid artery stenosis indexes by colour Doppler‐assisted duplex imaging. A critical appraisal of the parameters used

Abstract

The aim of our study was to establish colour Doppler-assisted duplex imaging (CDDI)-criteria to predict an angiographic internal carotid artery (ICA) stenosis of at least 70%, according to the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trialists (ECST) methods of measurement. In the following, we describe the findings in 79 patients who were screened for carotid endarterectomy by CDDI and further evaluated by digital subtraction angiography (DSA). In 158 carotid arteries, 107 stenoses of > 30% and nine occlusions were found. Receiver operator characteristic graphs were constructed in order to calculate sensitivities and specificities of the assessment by CDDI in the prediction of high-grade stenoses determined by angiography. Optimal cut-off points were defined by highest accuracy which reflects the combination of high sensitivity and specificity. The critical index of a high-grade ICA stenosis according to the ECST method could be predicted with an accuracy greater than 90% by a systolic peak velocitiy of 1.25 m/s or an area reduction by CDDI of 70%. Corresponding values, 1.6 m/s and 80% area reduction, predicted the stenosis indexes according to the NASCET method less reliably, with accuracies of between 80% and 90%. Flow velocity criterion was slightly less accurate than the area reduction criterion by CDDI. Finally, double-blind evaluation performed by two readers per examination modality showed that the measurement of area reduction in CDDI is at least as reliable as stenosis indexes according to ECST and NASCET methods.

Diagnostics and characterisation of preocclusive stenoses and occlusions of the internal carotid artery with B-flow

“…In addition, the angle-dependency of CCDS does not only influence the velocity measurement, but also the simultaneous establishment of the prestenotic, intrastenotic and poststenotic flow in the longitudinal scan, in particular for tortuous vessels [23][24][25]. Difficult conditions, such as a carotid bifurcation with relatively cranial location, a kinking of the vessel or distinct calcification in the vessel wall, can complicate the situation and lead to wrong diagnoses [4,7,11].…”

“…Selective X-ray digital subtraction angiography (DSA) has been the standard for evaluating the degree of ICA stenosis according to NASCET criteria [1,2,7,8,[10][11][12]. However, contrast medium-enhanced magnetic resonance angiography (MRA) and computed tomographic angiography (CTA) have the advantage of imaging the entire area supplied with blood via the carotid artery as well as providing additional three-dimensional (3D) maximum intensity projection (MIP) and multiplanar reformation (MPR) images [13][14][15].…”

“…It is difficult to differentiate preocclusive ICA stenoses from ICA occlusions using vascular ultrasonography because of the substantially diminished flow volume [4,7,11,[16][17][18]. Preliminary comparative investigations with vascular US techniques available hitherto, such as colourcoded Doppler sonography (CCDS) and power Doppler (PD) with selective DSA for appraisal of the stenosis with a new digital vascular US technique (B-flow), already indicated that there are advantages for intrastenotic flow detection in severe stenoses [28,30,36,37].…”

Color Doppler, power Doppler and B-flow ultrasound in the assessment of ICA stenosis: Comparison with 64-MD-CT angiography

“…In cases of preocclusive stenoses it is indispensable to establish the intra-stenotic and post-stenotic flow in order to differentiate an occlusion with partial re-canalisation [3,6,7,15], and all the ultrasound techniques under investigation reliably detected residual flow in the present study. However, CCDS is of limited usefulness for detecting preocclusive stenoses because intra-stenotic flow acceleration leads to reverberation artifacts.…”

“…ulcerated plaques and thrombi, is crucial for the planning of interventional treatment [1,2,5,7]. The selective intraarterial DSA is a reference standard for the grading of stenoses [1,2,[12][13][14][15][16]. For the evaluation of stenosis morphology, other imaging procedures such as vascular ultrasound, CTA or MRA can contribute information additional to intraarterial DSA [3,12,13,20].…”