Keywords:
Arteries / Aorta, Vascular, Computer applications, Ultrasound, Ultrasound-Colour Doppler, CT-Angiography, Diagnostic procedure, Computer Applications-Detection, diagnosis, Contrast agent-intravenous, Arteriosclerosis, Ischaemia / Infarction, Blood
Authors:
V. Rafailidis1, I. Chryssogonidis1, E. Grisan2, T. Tegos1, D. Rafailidis1, P. Sidhu2, A. Charitanti-Kouridou1, P. Prassopoulos1; 1Thessaloniki/GR, 2London/UK
DOI:
10.26044/ecr2019/C-0162
Aims and objectives
Carotid atherosclerosis represents an important cause of stroke,
with thromboembolism from a moderately or severely stenotic internal carotid artery plaque accounting for up to 15% of all cases [1].
Although the degree of stenosis has traditionally been regarded as the primary factor defining the risk for stroke,
a great number of studies have highlighted the importance of other factors as well.
Such features include plaque composition and surface morphology and the term “vulnerable plaque” has been introduced to describe those plaques associated with increased risk for neurovascular symptoms [2-7].
When it comes to surface morphology,
carotid plaques can be subjectively classified as smooth,
irregular or ulcerated.
Surface irregularities and ulceration have been consistently associated with increased risk for neurovascular symptoms such as transient ischemic attack and stroke and their evaluation is thus an important aspect of every imaging examination of the carotid arteries [8].
Ultrasound (US) with colour Doppler ultrasound (CDU) constitutes the primary imaging technique for evaluation of carotid disease and has the potential to assess plaque surface and diagnose ulceration with varying degrees of accuracy [8].
The introduction of microbubbles as ultrasonographic contrast agents has rendered contrast-enhanced ultrasound (CEUS) a valuable ultrasonographic technique for the evaluation of blood vessels including the carotid arteries [9].
A number of studies and publications have shown that CEUS is superior to CDU for the evaluation of carotid plaque surface irregularities and the diagnosis of ulceration [9,
10,
11,
12,
13].
This observation can be explained by the fact that CEUS offers increased sensitivity to slow flow,
improved contrast between blood and static tissues and is free of artifacts related to CDU such as blooming artifact,
aliasing and Doppler angle dependence.
However,
studies so far have demonstrated the superiority of CEUS over CDU using subjective assessment of the plaque.
It would be of interest to investigate whether CEUS would still outperform CDU if the diagnosis of ulceration would be based on an objective and quantitative measure of plaque surface irregularities,
thus confirming or rejecting the previous subjective observations.
This study’s purpose is thus to compare the diagnostic accuracy of these two techniques for detection of ulceration using an objective and quantitative measure of plaque surface irregularities.
The measure used is the Surface Irregularity Index (SII),
which is produced by using specialized software,
after manual delineation of the plaque.
The reference method for the diagnosis of ulceration used in this study is computed tomography angiography (CTA).