Invasive electrochemical impedance spectroscopy with phase delay for experimental atherosclerosis phenotyping

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Medical Imaging

Background:

• Distinguishing quiescent from rupture-prone atherosclerotic lesions is crucial for clinical management.
• Atherosclerosis characterization often requires multiple imaging modalities.
• Electrochemical impedance spectroscopy (EIS) assesses tissue electrical properties.

Purpose of the Study:

• To evaluate invasive 6-point stretchable EIS sensors for characterizing experimental atherosclerosis.
• To compare EIS findings with intravascular ultrasound (IVUS), positron emission tomography (PET) imaging, and histology.
• To determine the potential of EIS in comprehensively assessing atherosclerotic plaque features.

Main Methods:

• Experimental atherosclerosis was induced in New Zealand White rabbits using a high-fat diet and balloon injury.
• In vivo micro-PET imaging was performed using ⁶⁸Ga-DOTATATE, ¹⁸F-NaF, and ¹⁸F-FDG.
• Invasive assessments included intravascular ultrasound (IVUS) and electrochemical impedance spectroscopy (EIS), followed by histology.

Main Results:

• EIS impedance correlated with plaque activity markers like macrophage infiltration and macrophage/smooth muscle cell (SMC) ratio.
• EIS phase delay correlated with plaque burden markers, including intima/media ratio and % stenosis, similar to IVUS.
• PET tracers showed correlations with specific cellular components: ⁶⁸Ga-DOTATATE with macrophages, ¹⁸F-NaF with SMCs, and ¹⁸F-FDG with macrophage/SMC ratio.

Conclusions:

• Invasive EIS, particularly phase delay, effectively integrates key atherosclerosis features typically requiring multiple imaging techniques.
• EIS demonstrates potential as a comprehensive tool for evaluating human coronary artery disease.
• EIS offers a promising approach for detailed atherosclerotic lesion characterization.