Intravascular ultrasound elastography: an overview

Area of Science:

• Cardiovascular Medicine
• Biomedical Engineering
• Medical Imaging

Background:

• Atherosclerotic plaque composition and morphology are crucial in acute coronary syndromes, often more so than stenosis degree.
• Unstable plaques with thin fibrous caps and large lipid pools are prone to rupture, leading to thrombosis.
• Macrophage infiltration can further weaken plaque caps, increasing rupture risk.

Purpose of the Study:

• To evaluate intravascular ultrasound elastography as a tool for assessing mechanical properties of atherosclerotic lesions.
• To differentiate between plaque types (fibrous, fibro-fatty, fatty) based on mechanical characteristics.
• To validate the feasibility of intravascular elastography for in vivo application in animal models and patients.

Main Methods:

• Intravascular ultrasound elastography was developed, using intraluminal pressure as an excitation force to measure tissue deformation.
• In vitro validation involved human coronary and femoral arteries, correlating elastographic strain with histological findings.
• In vivo validation was performed in Yucatan mini-pigs and subsequently in patients undergoing Percutaneous Transluminal Coronary Angioplasty.

Main Results:

• In vitro studies showed significant differences in strain values among fibrous, fibro-fatty, and fatty plaque types (p < 0.001).
• In vivo validation in mini-pigs confirmed higher strain values in fatty plaque material (p < 0.001).
• Patient data demonstrated distinct strain patterns for soft plaques (1-2%), calcified plaques (0-0.2%), and stented plaques.

Conclusions:

• Intravascular ultrasound elastography is a promising technique for evaluating the local mechanical properties of atherosclerotic lesions.
• The method effectively distinguishes between fibrous and fatty tissue, crucial for identifying vulnerable plaques.
• Feasibility for in vivo application in clinical settings has been demonstrated.