Layer-specific ultrasound elastography using a multi-layered shear wave dispersion model for assessing the...

Area of Science:

• Biomedical Engineering
• Biophysics
• Medical Imaging

Background:

• Mechanical properties of biological tissues are crucial biomarkers for disease diagnosis.
• Assessing viscoelastic properties of multi-layer tissues using shear wave models has been challenging.
• Existing models are limited as most biological tissues are not single-layered.

Purpose of the Study:

• To propose and validate a novel multi-layer model for layer-specific viscoelasticity estimation.
• To integrate a theoretical model with an ultrasonic micro-elastography imaging system.
• To enhance the accuracy and expand clinical applications of shear wave elastography for complex tissues.

Main Methods:

• Developed a multi-layer theoretical model for viscoelasticity estimation.
• Integrated the model with an ultrasonic micro-elastography imaging system.
• Validated the model using dual-layer phantoms and ex vivo porcine eyes, comparing results with mechanical tests and bulk rheological models.

Main Results:

• The proposed multi-layer model accurately estimated viscoelastic properties of dual-layer phantoms, showing consistency with mechanical tests (p < 0.1).
• Estimated moduli for phantoms: 1.3 ± 0.2 kPa and 16.20 ± 1.8 kPa (elastic), 0.80 ± 0.31 Pa·s and 1.87 ± 0.67 Pa·s (viscosity).
• Demonstrated significantly higher accuracy compared to group velocity and single-layer Rayleigh-Lamb models, with accurate measurements in ex vivo porcine eye tissues (retina and sclera).

Conclusions:

• The proposed multi-layer model significantly improves the accuracy of layer-specific viscoelasticity estimation in biological tissues.
• This method overcomes limitations of previous models, expanding the potential clinical applications of shear wave elastography.
• The validated model offers a more precise tool for diagnosing diseases through mechanical property assessment of complex biological structures.