Ultrasound Localization Microscopy in Identifying High-Risk Carotid Plaque Using Low-Frame-Rate Ultrasound Imaging.

Area of Science:

• Vascular Biology and Imaging
• Cardiovascular Research
• Medical Ultrasound Technology

Background:

• Intra-plaque neovascularization (IPN) is a key factor in carotid plaque progression, instability, and ischemic stroke risk.
• Conventional contrast-enhanced ultrasound (CEUS) has limitations in visualizing the microvasculature within atherosclerotic plaques.
• Differentiating symptomatic from asymptomatic carotid plaques is crucial for clinical management and stroke prevention.

Purpose of the Study:

• To evaluate the feasibility of ultrasound localization microscopy (ULM) for characterizing carotid plaque microvasculature.
• To assess ULM's ability to differentiate symptomatic from asymptomatic carotid plaques using microvascular features.
• To explore ULM's potential for quantitative imaging biomarkers in carotid atherosclerosis.

Main Methods:

• Prospective inclusion of 65 patients with 78 carotid atherosclerotic plaques evaluated by clinical CEUS.
• Application of ULM to localize and track microbubbles at a subwavelength scale for high-resolution imaging.
• Analysis of anatomical (microvessel density, length, tortuosity) and functional (blood velocity) features.

Main Results:

• ULM successfully visualized IPN with significantly higher resolution than conventional CEUS.
• Symptomatic plaques exhibited significantly higher IPN density (microbubble counts, track counts, path length) and blood velocity compared to asymptomatic plaques (p < 0.05).
• Quantitative imaging biomarkers derived from ULM demonstrated significant differences between symptomatic and asymptomatic carotid plaques.

Conclusions:

• ULM provides high-resolution visualization of intra-plaque neovascularization in carotid atherosclerosis.
• Quantitative microvascular features obtained by ULM can effectively differentiate symptomatic from asymptomatic plaques.
• ULM coupled with CEUS shows potential as a diagnostic tool for patient stratification and guiding therapeutic decisions in carotid artery disease.