Atherosclerotic Carotid Plaques: Multimodality Imaging with Contrast-enhanced Ultrasound, Computed Tomography, and Magnetic Resonance Imaging

Novel theranostic approaches to neovascularized atherosclerotic plaques

As the global burden of atherosclerotic cardiovascular disease continues to rise, there is an increased demand for improved imaging techniques for earlier detection of atherosclerotic plaques and new therapeutic targets. Plaque lesions, vulnerable to rupture and thrombosis, are thought to be responsible for the majority of cardiovascular events, and are characterized by a large lipid core, a thin fibrous cap, and neovascularization. In addition to supplying the plaque core with increased inflammatory factors, these pathological neovessels are tortuous and leaky, further increasing the risk of intraplaque hemorrhage. Clinically, plaque neovascularization has been shown to be a significant and independent predictor of adverse cardiovascular outcomes. Microvessels can be detected through contrast-enhanced ultrasound (CEUS) imaging, however, clinical assessment in vivo is generally limited to qualitative measures of plaque neovascularization. There is no validated standard for quantitative assessment of the microvessel networks found in plaques. Advances in our understanding of the pathological mechanisms underlying plaque neovascularization and its significant role in the morbidity and mortality associated with atherosclerosis have made it an attractive area of research in translational medicine. Current areas of research include the development of novel therapeutic and diagnostic agents to target plaque neovascularization stabilization. With recent progress in nanotechnology, nanoparticles have been investigated for their ability to specifically target neovascularization. Contrast microbubbles have been similarly engineered to carry loads of therapeutic agents and can be visualized using CEUS. This review summarizes the pathogenesis, diagnosis, clinical significance of neovascularization, and importantly the emerging areas of theranostic tool development.

Carotid Intraplaque Neovascularization on Contrast-Enhanced Ultrasound Correlates with Cardiovascular Events and Poor Prognosis: A Systematic Review and Meta-analysis

The goal of this meta-analysis is to investigate whether carotid intraplaque neovascularization (IPN) on contrast-enhanced ultrasound (CEUS) correlates with past cardiovascular events (CVEs) and prognosis. The present meta-analysis included 22 studies involving 3232 patients. The pooled analysis revealed that the presence of IPN was significantly associated with a higher incidence of future CVEs (pooled relative risk = 3.28, 95% confidence interval [CI]: 2.28-4.73) and a lower event-free probability (pooled hazard ratio = 2.51, 95% CI: 1.48-4.27). The presence of IPN was significantly associated with higher rates of past cardiac events (odds ratio = 4.25, 95% CI: 2.48-7.29) and past cerebrovascular accidents (odds ratio = 4.83, 95% CI: 2.66-8.78). Our results suggest that carotid IPN on CEUS significantly correlates with past cardiac events and cerebrovascular accidents and can predict future CVEs. Carotid CEUS is useful in CVE risk stratification.

Carotid angle in young stroke

PURPOSE

To investigate whether the carotid bifurcation angle as assessed by computed tomographic angiography (CTA) is associated with anterior circulation ischemic stroke (ACIS) in young patients.

MATERIAL AND METHODS

Thirty patients (mean age 41.5 ± 6 years) with known acute ACIS (group 1) were compared to 30 control patients (mean age/ 41.2 ± 6 years) (group 2) with similar demographic variables in this retrospective study. Geometrical characteristics of bilateral carotid bifurcation were obtained by CTA. The ICA bifurcation (ICAB) angle, the carotid central bifurcation (CCB), and the carotid bifurcation wall (CBW) angle among the ICA, CCA, and ECA were measured. Carotid artery angle measurements were compared between group 1 and group 2. The comparison of pathological (ACIS) and non-pathological (non-ACIS) carotid sides in group 1 was performed as well.

RESULTS

All the measured angles (AMA) of group 1 were higher than group 2 (p˂0.05). In patients with left-sided ACIS, AMA on the left side were higher than the right side (p˂0.05), this was more prominent in males (p˂0.05). All angles measured were found to be higher in ipsilateral ACIS (p˂0.05). The left CCB angle values had a significant effect on ischemic stroke (p˂0.05). Male patients had more left-sided ACIS (p˂0.05). Plaque development in ICA was found statistically significant in group 1 compared to group 2 (p˂0.05).

CONCLUSION

Carotid artery geometry may play an important role in the development of ischemic events in young patients, especially in men and, also in patients with left-sided stroke. The left CCB angle had a significant effect on ACIS.

Plaque imaging volume analysis: technique and application

The prevention and management of atherosclerosis poses a tough challenge to public health organizations worldwide. Together with myocardial infarction, stroke represents its main manifestation, with up to 25% of all ischemic strokes being caused by thromboembolism arising from the carotid arteries. Therefore, a vast number of publications have focused on the characterization of the culprit lesion, the atherosclerotic plaque. A paradigm shift appears to be taking place at the current state of research, as the attention is gradually moving from the classically defined degree of stenosis to the identification of features of plaque vulnerability, which appear to be more reliable predictors of recurrent cerebrovascular events. The present review will offer a perspective on the present state of research in the field of carotid atherosclerotic disease, focusing on the imaging modalities currently used in the study of the carotid plaque and the impact that such diagnostic means are having in the clinical setting.

Non-invasive imaging techniques and assessment of carotid vasa vasorum neovascularization: Promises and pitfalls

Carotid adventitia vasa vasorum neovascularization (VVn) is associated with the initial stages of arteriosclerosis and with the formation of unstable plaque. However, techniques to accurately quantify that neovascularization in a standard, fast, non-invasive, and efficient way are still lacking. The development of such techniques holds the promise of enabling wide, inexpensive, and safe screening programs that could stratify patients and help in personalized preventive cardiovascular medicine. In this paper, we review the recent scientific literature pertaining to imaging techniques that could set the stage for the development of standard methods for quantitative assessment of atherosclerotic plaque and carotid VVn. We present and discuss the alternative imaging techniques being used in clinical practice and we review the computational developments that are contributing to speed up image analysis and interpretation. We conclude that one of the greatest upcoming challenges will be the use of machine learning techniques to develop automated methods that assist in the interpretation of images to stratify patients according to their risk.