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Clinical/methodical Issue: The aim was to identify the risk of impending stroke originating from diseases of the carotid artery., Standard Radiological Methods: Duplex scanning is the standard method for clinical examination of carotid arteries., Methodical Innovations: By implementing the new standardized German Society for Ultrasound in Medicine (DEGUM) criteria, ultrasound examination enables reliable grading of carotid artery disease and identification of the progression of stenosis., Performance: Current guidelines recommend duplex scanning as the standard method. In consequence of finding atherosclerosis, intensive monitoring and therapy of cardiovascular risk factors is mandatory. In cases showing rapid progression of stenosis or a very high degree of stenosis indicating increased risk of stroke, carotid endarterectomy or stenting is warranted., Achievements: Detection of carotid artery atherosclerosis is uncomplicated and the method is not demanding; however, identification of high-risk carotid disease by exact grading of carotid stenosis requires investigation by an experienced examiner., Practical Recommendations: Screening is recommended for patients exhibiting cardiovascular risk factors but is not recommended for the general population. On detection of carotid stenosis an exact grading of stenosis by an experienced examiner is absolutely essential.

Since 1986, German ultrasound criteria for grading carotid stenosis have followed the local diameter reduction percentage consistent with the definition used in the European Carotid Surgery Trial (ECST) definition. To overcome the confusion caused by the coexisting grading method used in the North American Symptomatic Carotid Endarterectomy Trial (NASCET), a German interdisciplinary council on carotid artery stenosis has recommended the implementation of the NASCET grading system (distal diameter reduction percentage) as the standard. The multi-parametric German "DEGUM ultrasound criteria" consisting of combined Doppler and imaging criteria have consequently been revised and transferred to the NASCET definition. In addition, a novel differentiation between main (primary) and additional (secondary) criteria has been proposed. When these ultrasound criteria are combined, vascular sonography allows reliable grading of carotid disease., (Copyright Georg Thieme Verlag KG Stuttgart . New York.)

Aim: To evaluate the usefulness of various sonographic criteria for detecting a dissection of the internal carotid artery (ICA)., Method: Twenty-three consecutive patients displaying typical clinical symptoms of ICA dissection were identified. The diagnosis of dissection in these cases was confirmed by MRI/MRA or arteriography. The sonographic examination was the first technical investigation and involved the combined use of Doppler and duplex sonography. The value of different sonographic criteria was evaluated for the identification of ICA dissection: 1) Morphological criteria: intramural haematoma or double lumen. 2) Haemodynamic findings of distal stenosis/occlusion in combination with suddenly appearing clinical signs of a space-occupying lesion in the respective region (Horner's syndrome, lower cranial nerve palsies). 3) Haemodynamic signs of distal stenosis/occlusion with ensuing recanalisation within a few weeks., Results: Morphological criteria alone allowed detection of a dissection in 47,8 % of patients. By the combined use of morphological and haemodynamic criteria ICA dissections were identified on admission in 73.9 % and after an average of 4.5 weeks (at the latest after 6 weeks) in 91.3 % of the patients., Conclusion: ICA dissections can be identified sonographically with high sensitivity. In some of the cases, however, definite diagnosis can only be provided by follow-up evaluation.

Determining degree and morphology of stenoses is important for surgical planning or stent implantation. Vascular ultrasound is usually the first modality to evaluate carotid artery stenosis. Due to rapid development various methods of vascular ultrasound are applied including continuous wave (CW) Doppler, duplex Doppler, colour-coded duplex sonography (CCDS), power Doppler and B-flow technique. For quantitative assessment of the degree of stenosis the most frequently used parameters are peak systolic velocity (PSV), end-diastolic velocity (EDV) in the internal carotid artery (ICA), as well as ICA to CCA ratios of PSV and EDV. Different results reported in the literature may reflect differences in defining the degree of stenosis and methodological differences in protocol or imaging techniques. Differences in defining the degree of stenosis, advantages and disadvantages of the different Doppler techniques and future developments are discussed in detail.

Unlabelled: Therapeutic decisions in cases of arteriosclerotic stenosis of the internal carotid artery usually depend mainly on the degree of stenosis. However, the recommendations with regard to suitable ultrasonographic criteria are so controversial that even authors of repute describe "confusion" and "chaos in methodology"., Aim: The aim of this study is to assess which of the most frequently recommended sonographic criteria for stenosis best fulfill the requirements of an exact quantification of stenoses of the internal carotid artery., Method: In 42 consecutive cases the preoperative ultrasound findings were compared with the degree of stenosis in surgically removed specimens. The sonographic technique employed consisted of the analysis of 2 direct and 3 indirect hemodynamic criteria of stenosis. In 34 of these cases planimetry was performed, too. The specimens were obtained by eversion thrombendarteriectomy or arteriotomy; for determination of the degree of stenosis a Paladur molded cylinder was prepared and measured., Results: Quantification of the haemodynamic criteria carries provided well with the endarterectomy specimens. Only in two cases there was a deviation of more than 10 %; however, in these two cases a change with time in the degree of stenosis was probably responsible for the discrepancy. In contrast, planimetry usually underestimated the degree of stenosis: In 61 % of the findings the ultrasonographic results differed by more than 10 % from the reference standard., Conclusion: Quantification of stenosis of the internal carotid artery should be made using a combination of direct and indirect haemodynamic ultrasonographic criteria.

The aim of this study was to assess the current value of extracranial continuous wave (cw) Doppler sonography in routine use as compared to color-coded duplex sonography. For this purpose, 500 carotid and 500 vertebral arteries were examined by a user experienced in both methods. The error rate of Doppler sonography was determined only when the methods allowed a clear decision to be made about the status of the vessel (normal findings including common variants, stenosis, and occlusion). In 85.4% of the carotid arteries and 88% of the vertebral arteries, the Doppler findings fulfilled the diagnostic differentiation unequivocally. For these cases, false findings were obtained in 1.9% of the carotid arteries and 0.2% of the vertebral arteries. Accordingly, a clear Doppler sonographic finding, normal or pathologic, is still of large diagnostic value. However, ambiguous or uncertain findings requiring further diagnostic workup are not uncommon. Thus, the sole use of cw Doppler sonography is no longer sufficient in a stroke center but still retains its utility in the practitioner's office.

Unlabelled: Perivascular tissue vibrations, an artefact of the colour Doppler method, are already known to be a sonographic sign of stenosis but have not yet been investigated systematically in the examination of the internal carotid artery., Aim: The present study is intended to assess the value of this artefact in the diagnosis of stenosis of the internal carotid artery., Method: A total of 167 consecutive cases including a stenosis of the internal carotid artery of at least 50% were diagnosed according to the usual haemodynamic criteria using Doppler and duplex sonography and classified into 10% categories. Intermediate groups were formed for findings that could not be assigned unambiguously. By means of suitable apparatus settings each finding was examined to test whether a perivascular colour artefact was detectable., Results: In the stenosis categories of 50% to 70% no perivascular colour artefact was found, whereas in the stenosis categories of 80% to 90% this was the case in 80% of the findings, and in the intermediate 75% category in 42% of the findings. The perivascular colour artefact was recognizable even under poor sonographic conditions., Conclusion: When a perivascular colour artefact is seen the diagnosis of a high-degree stenosis (or an AV fistula) is certain. The phenomenon is particularly valuable as a supplementary criterion of stenosis in cases of unfavourable sonographic conditions. However, the perivascular colour artefact may only be used to confirm, but never to exclude, a high-degree stenosis.

A knowledge of mirror image artifacts in color-coded duplex sonography is important as they can lead to diagnostic problems in the morphologic evaluation of stenoses and plaques. Mirror image artifacts were detectable in stenosed vessels when strongly reflecting plaques on the wall of the vessel distant from the transducer head were insonated obliquely. The artifacts were revealed in regions that were hypoechoic or anechoic on B-mode scans. Depending on the angle of insonation and the surface structure of the plaque, the mirror image artifact could be linked with the vessel lumen and thus imitate ulcerations or branches. The artifact appeared in both the longitudinal and the transverse projections and also occurred in the power Doppler and in pulsed Doppler sonographic modes. Mirror image artifacts with linkages to the vessel lumen that could result in a misinterpretation were seen in 2.5% of the stenosed vessels.