Contrast-enhanced ultrasound of the carotid system: a review of the current literature

Abstract

Carotid disease is a major current health problem accounting for a significant part of stroke patients. Ultrasound with colour Doppler and spectral analysis is the primary imaging technique used for screening and diagnostic evaluation of the extracranial part of carotid arteries offering identification and grading of carotid disease. However, inherent limitations of this technique include flow-related artefacts like Doppler angle dependence and aliasing artefact which may sometimes hinder complete assessment of a stenotic part of the vessel, potentially failing to address clinically significant differential diagnosis issues. The intravenous use of microbubbles as an US contrast agent has been introduced for the supplementation of conventional technique. The value of contrast-enhanced ultrasound (CEUS) has been investigated in the evaluation of carotid disease leading to promising results. CEUS provides improved flow visualization free of artefacts and detailed plaque surface delineation, thus being able to accurately grade stenosis, identify carotid plaque ulcerations, differentiate occlusion from highly stenotic plaques and identify carotid dissection. Furthermore, microbubbles can be used to identify and grade intraplaque neovascularization, carotid wall inflammation in patients with arteritis, follow-up patients after carotid intervention and assist interventional procedures reducing the need for nephrotoxic contrast agents. The purpose of this review is to present and discuss the current literature regarding the various uses of CEUS in carotid arteries.

Ultrasound Microbubbles for Diagnosis and Treatment of Cardiovascular Diseases

“…However, CEUS could still detect blood flow within the highly stenotic artery around the irregular plaque. These findings were in line with multidetector computed tomographic angiography (MDCTA) (adapted from Rafailidis et al 7 ). (B) Grading of intraplaque neovascularization (IPN) using CEUS: Mild (grade I) IPN is characterized by the presence of moving microbubbles only on the adventitial plaque side (arrows).…”

“…Newly build vessels within the plaques are prone to rupture, can lead to intraplaque hemorrhage, increase the infiltration of inflammatory cells, facilitate the transport of lipids into the plaque, and therefore can lead to plaque enlargement and rupture. 7 Neovascularization assessed by CEUS showed a good correlation with histology 7 and Saha et al described a grading system for characterization of plaque neovascularization that can be divided into three categories: (a) mild: presence of moving microbubbles only at the plaque border, near adventitia; (b) moderate: microbubbles present at plaque shoulder and inside, but not at the apex; (c) severe: microbubbles present throughout the plaque including the apex 26 (►Fig. 2).…”

“…6 To overcome these limitations, the use of gas-filled microbubbles as intravascular contrast agents has been approved for clinical cardiac US imaging. 7 Beside the approved clinical indications for CEUS, this review article summarizes and discusses emerging technologies and applications of molecular CEUS that either are in advanced preclinical evaluation stages or already in clinical trials (►Table 1).…”

Validation of Multiparametric Ultrasonography Criteria with Digital Subtraction Angiography in Carotid Artery Disease: A Prospective Multicenter Study

“…It is still unclear whether the test performance of DUS carotid disease grading is generally limited by its technical ability and whether further adjustments in ultraso-nography criteria may eventually result in an increase in diagnostic accuracy in contrast to the results of a recent correlation analysis [7]. On the other side, advanced methods such as plaque imaging and the utilization of contrast agents might aid in the identification of patients who may benefit from revascularization procedures, regardless of the degree of stenosis [25].…”

Plaque neovascularization detected with contrast‐enhanced ultrasound predicts ischaemic stroke recurrence in patients with carotid atherosclerosis

“…Contrast‐enhanced ultrasound (CEUS) can visualize neovessels within carotid atherosclerotic plaques in vivo . This technique uses an ultrasound (US)‐specific contrast made of microbubbles containing an echogenic component such as phospholipid‐encapsulated sulphur hexafluoride.…”