The inter-observer agreement in the assessment
of carotid plaque neovascularization by contrast-enhanced
ultrasonography: The impact of plaque thickness
Jian Chen MB
Yan-Ming Zhang MB
Ze-Zhou Song MS
Yan-Fei Fu MB
Yu Geng MD
Department of Ultrasound, The Fourth
Affiliated Hospital, College of Medicine,
Zhejiang University, Yiwu, China
Department of Ultrasound, Zhejiang
Provincial People’s Hospital, and Affiliated
People’s Hospital of Hangzhou Medical
College, Hangzhou, China
Community Health Centre in Binjiang
District, Hangzhou, China
Department of Neurology, Zhejiang
Provincial People’s Hospital, Hangzhou,
Z.-Z. Song, #158 Shangtang Road,
Hangzhou, Zhejiang Province 310014,
People’s Republic of China.
Background: The interobserver agreement in the assessment of the grade of carotid plaque neo-
vascularization by contrast-enhanced ultrasonography is poorly established.
Method: We examined 140 carotid plaques in 66 patients (all patients had bilateral plaques, and 8
patients had 2 plaques on one side). We performed conventional and contrast-enhanced ultraso-
nography to analyze the presence of carotid plaque neovascularization, which was graded by two
independent observers whose interobserver agreement (j) was evaluated according to the thick-
ness of carotid plaque.
Results: For all carotid plaques, the mean j was 0.689 (95% confidence interval 0.604-0.774). It
was 0.689 (0.569-0.808), 0.637 (0.487-0.787), and 0.740 (0.585-0.896), respectively for carotid
plaques with maximal thickness <2 mm, from 2 mm to 3 mm, and >3mm.
Conclusion: The interobserver agreement for assessing carotid plaque neovascularization by using
contrast-enhanced ultrasonography is substantial and acceptable for research purposes, regardless
of the maximal thickness of the plaque.
carotid plaque, contrast-enhanced ultrasonography, interobserver agreement, neovascularization
As in the aging American population, in which approximately 750,000
strokes occur each year, stroke is one of the leading causes of morbid-
ity and mortality worldwide. This is likely to worsen in the future
because of the increasing prevalence of obesity, metabolic syndrome,
and clinical diabetes. It is well known that carotid artery atherosclerosis
is closely associated with stroke events.
The atherosclerosis develop-
ment results in ischemia of the vessel wall, which causes a continual
release of angiogenic growth factors promoting neovascularization.
The immature neovessels, without pericytes, leak toxic, and inflamma-
tory plasma component contributing to the plaque development.
degree of neovascularization is associated with plaque vulnerability,
increasing the risk of rupture, which cause thrombosis and embolism.
Therefore, the neovascularization of carotid plaques has been well
established as a consistent feature of their vulnerability.
As the microbubbles of ultrasound contrast agents are suitable
intravascular tracers, the appearance of contrast within carotid plaques
suggests the presence of neovascularization.
showed that the quantitative and semiquantitative of contrast-
enhancement is associated with the density of neovascularization of
The use of contrast-enhanced ultrasonography to
assess carotid intraplaque neovascularization and vulnerability, would
Ethics approval and consent to participate: The protocol was approved by the
ethical committee of Zhejiang Provincial People’s hospital.
Consent for publication: All authors and participants have signed consent for
Available of data and material: Please contact author for data requests.
J Clin Ultrasound. 2018;46:403–407. wileyonlinelibrary.com/journal/jcu
2018 Wiley Periodicals, Inc.
Received: 19 June 2017
Revised: 16 March 2018
Accepted: 20 March 2018