Phase-Domain Photoacoustic Mechanical Imaging for Quantitative Elastography and Viscography

Area of Science:

• Biophysics
• Biomedical Engineering
• Medical Imaging

Background:

• Cell and tissue mechanical properties are crucial in disease.
• Current elastography methods are limited by wave propagation directionality.
• Accurate measurement of viscoelasticity is needed for mechanopathology diagnosis.

Purpose of the Study:

• To introduce phase-domain photoacoustic mechanical imaging (PD-PAMI) for quantitative viscoelastic property extraction.
• To validate PD-PAMI's accuracy and scalability across different length scales.
• To demonstrate PD-PAMI's utility in monitoring disease-related biomechanical changes.

Main Methods:

• Utilizing omnidirectional photoacoustic elastic waves and their initial time/phase responses.
• Performing theoretical simulations and phantom experiments to assess elasticity and viscosity estimation.
• Conducting trans-scale viscoelasticity mapping from cellular to in vivo organ levels.
• Applying PD-PAMI to animal models of breast tumor and atherosclerosis.

Main Results:

• Achieved high precision in elasticity (4.6%) and viscosity (6.6%) estimation.
• Demonstrated scalability of PD-PAMI across cellular, tissue, and organ scales.
• Successfully monitored viscoelastic parameter variations in disease models.
• Showcased PD-PAMI's ability to detect changes related to collagen, lipid, and inflammation.

Conclusions:

• PD-PAMI offers a novel, quantitative approach to biomechanical imaging.
• The technique enhances conventional photoacoustic imaging capabilities.
• PD-PAMI shows significant potential for clinical diagnosis of mechanopathology-involved diseases.