Semiautomated Magnetic Resonance Imaging Assessment of Carotid Plaque Lipid Content

Diagnostic potential of TSH to HDL cholesterol ratio in vulnerable carotid plaque identification

Objective

This study aimed to investigate the predictive value of the thyroid-stimulating hormone to high-density lipoprotein cholesterol ratio (THR) in identifying specific vulnerable carotid artery plaques.

Methods

In this retrospective analysis, we included 76 patients with carotid plaques who met the criteria for admission to Zhejiang Hospital from July 2019 to June 2021. High-resolution magnetic resonance imaging (HRMRI) and the MRI-PlaqueView vascular plaque imaging diagnostic system were utilized to analyze carotid artery images for the identification of specific plaque components, including the lipid core (LC), fibrous cap (FC), and intraplaque hemorrhage (IPH), and recording of the area percentage of LC and IPH, as well as the thickness of FC. Patients were categorized into stable plaque and vulnerable plaque groups based on diagnostic criteria for vulnerable plaques derived from imaging. Plaques were categorized based on meeting one of the following consensus criteria for vulnerability: lipid core area over 40% of total plaque area, fibrous cap thickness less than 65 um, or the presence of intraplaque hemorrhage. Plaques meeting the above criteria were designated as the LC-associated vulnerable plaque group, the IPH-associated group, and the FC-associated group. Multivariate logistic regression was employed to analyze the factors influencing carotid vulnerable plaques and specific vulnerable plaque components. Receiver operating characteristic (ROC) curves were used to assess the predictive value of serological indices for vulnerable carotid plaques.

Results

We found that THR (OR = 1.976; 95% CI = 1.094-3.570; p = 0.024) and TSH (OR = 1.939, 95% CI = 1.122-3.350, p = 0.018) contributed to the formation of vulnerable carotid plaques. THR exhibited an area under the curve (AUC) of 0.704 (95% CI = 0.588-0.803) (p = 0.003), and the AUC for TSH was 0.681 (95% CI = 0.564-0.783) (p = 0.008). THR was identified as an independent predictor of LC-associated vulnerable plaques (OR = 2.117, 95% CI = 1.064-4.212, p = 0.033), yielding an AUC of 0.815. THR also demonstrated diagnostic efficacy for LC-associated vulnerable plaques.

Conclusion

This study substantiated that THR and TSH have predictive value for identifying vulnerable carotid plaques, with THR proving to be a more effective diagnostic indicator than TSH. THR also exhibited predictive value and specificity in the context of LC-associated vulnerable plaques. These findings suggest that THR may be a promising clinical indicator, outperforming TSH in detecting specific vulnerable carotid plaques.

Advanced ultrasound methods in assessment of carotid plaque instability: a prospective multimodal study

Background

A significant proportion of ischemic strokes are caused by emboli from atherosclerotic, unstable carotid artery plaques. The selection of patients for endarterectomy in current clinical practice is primarily based on the degree of carotid artery stenosis and clinical symptoms. However, the content of the plaque is known to be more important for stroke risk. Intraplaque neovascularization (IPN) has recently emerged as a possible surrogate marker for plaque instability. Neo-microvessels from the adventitial vasa vasorum grow into the full thickness of the vessel wall in an adaptive response to hypoxia, causing subsequent intraplaque haemorrhage and plaque rupture. Conventional ultrasound cannot detect IPN. Contrast-enhanced ultrasound and Superb Microvascular Imaging (SMI), have, however, shown promise in IPN assessment. Recent research using Shear Wave Elastography (SWE) has also reported reduced tissue stiffness in the artery wall (reduced mean Young’s modulus) in unstable compared to stable plaques. The purpose of this study is to identify unstable carotid artery plaques at risk of rupture and future ischemic stroke risk using multimodal assessments.

Methods

Forty five symptomatic and 45 asymptomatic patients > 18 years, with > 50% carotid stenosis referred to Oslo University Hospital ultrasound lab will be included in this on-going project. Patients will undergo contrast enhanced ultrasound, SMI, carotid-MRI and PET-(¹⁸F-FDG). Contrast enhanced ultrasound will be analyzed semi-quantitatively (5-levels visual classification) and quantitatively by plotting time-intensity curve analyses to obtain plaque peak contrast enhancement intensity. Plaques removed at carotid endarterectomy will be assessed histologically and the number of microvessels, areas of inflammation, granulation, calcification, lipid and fibrosis will be measured.

Discussion

This multimodality study will primarily provide information on the clinical value of advanced ultrasound methods (SMI, SWE) for the detection of unstable carotid artery plaque in comparison with other methods including contrast-enhanced ultrasound, carotid-MRI and PET-(¹⁸F-FDG) using histology as the gold standard. Secondly, findings from the methods mentioned above will be related to cerebrovascular symptoms, blood tests (leukocytes, CRP, ESR, lipoproteins and inflammatory markers) and cardiovascular risk factors at inclusion and at 1-year follow-up. The overall aim is to optimize detection of plaque instability which can lead to better preventive decisions and reduced stroke rate.

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.

Unstable carotid artery plaque: new insights and controversies in diagnostics and treatment

Cardiovascular disease is estimated to be the leading cause of death, globally causing 14 million deaths each year. Stroke remains a massive public health problem and there is an increasing need for better strategies for the prevention and treatment of this disease. At least 20% of ischemic strokes are thromboembolic in nature, caused by a thromboembolism from an atherosclerotic plaque at the carotid bifurcation or the internal carotid artery. Current clinical guidelines for both primary and secondary prevention of stroke in patients with carotid stenosis caused by atherosclerotic plaques remain reliant on general patient characteristics (traditional risk factors for stroke) and static measures of the degree of artery stenosis. Patients with similar traditional risk factors, however, have been found to have different risk of stroke, and it has in recent years become increasingly clear that the degree of artery stenosis alone is not the best estimation of stroke risk. There is a need for new methods for the assessment of stroke risk to improve risk prediction for the individual patient. This review aims to give an overview of new methods available for the identification of carotid plaque instability and the assessment of stroke risk.