Perivascular colour artefact, a criterion of high-grade internal carotid artery stenoses

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 70% 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 90% 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.