Three-Dimensional Subharmonic Aided Pressure Estimation for Assessing Arterial Plaques in a Rabbit Model.

Area of Science:

• Cardiovascular Imaging
• Biomarkers for Atherosclerosis
• Medical Ultrasound Technology

Background:

• Atherosclerotic plaques pose a risk for cardiovascular events.
• Accurate measurement of intraplaque pressure and pressure gradients is crucial for assessing plaque vulnerability.
• Novel imaging techniques are needed to non-invasively evaluate these parameters.

Purpose of the Study:

• To evaluate the efficacy of 3-dimensional subharmonic aided pressure estimation (SHAPE) for measuring intraplaque pressure.
• To assess the pressure gradient across the plaque cap using SHAPE.
• To explore SHAPE-derived metrics as potential biomarkers for predicting plaque vulnerability.

Main Methods:

• Arteriosclerotic plaques were induced in rabbits via a high-cholesterol diet and balloon catheter injury.
• 3D SHAPE imaging was performed at 12, 16, and 20 weeks post-injury using ultrasound contrast agents (Definity and Sonazoid).
• Correlations were analyzed between SHAPE-derived subharmonic magnitudes and directly measured intraplaque pressure and pressure gradients.

Main Results:

• The study experienced significant rabbit mortality and exclusion rates, limiting the sample size.
• Developed plaques were small even after 20 weeks.
• Definity demonstrated moderate correlations with pressure gradients (r=-0.40) and intraplaque pressure (r=-0.19), while Sonazoid showed weaker correlations.

Conclusions:

• 3D SHAPE technique yielded only moderate correlations with direct pressure measurements in this animal model.
• The limitations of the animal model may have impacted the observed correlations.
• Further refinement of the technique and validation in larger plaque models are warranted.