Perivascular tissue vibrations: a criterium for high-grade stenoses of the internal carotid artery

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. The present study is intended to assess the value of this artefact in the diagnosis of stenosis of the internal carotid artery. 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. 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. 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.