Photoacoustic spectrum analysis for microstructure characterization in biological tissue: analytical model

Area of Science:

• Biomedical Optics
• Acoustics
• Signal Processing

Background:

• Photoacoustic spectrum analysis (PASA) shows potential for microstructure identification in phantoms and biological tissues.
• PASA utilizes ultrasound spectrum analysis principles, despite differing signal generation mechanisms between ultrasound backscatter and photoacoustic wave generation.

Purpose of the Study:

• To theoretically validate the application of Photoacoustic spectrum analysis (PASA) for microstructure characterization.
• To derive an analytical solution for the power spectrum of photoacoustic signals from spatially randomly distributed microspheres.

Main Methods:

• Derivation of an analytical solution for the power spectrum of photoacoustic signals from identical microspheres with a uniform random spatial distribution.
• Simulation and experimental validation of the derived analytical solution.
• Analysis of the power spectrum profile of single microspheres (300 μm diameter) and PASA parameters for various microsphere sizes (100–500 μm) and concentrations.

Main Results:

• The study successfully derived an analytical solution for the power spectrum of photoacoustic signals from randomly distributed microspheres.
• Validation through simulations and experiments confirmed the analytical solution's accuracy.
• PASA parameters were analyzed across a range of microsphere sizes and concentrations, demonstrating the method's capability.

Conclusions:

• The theoretical validation confirms PASA's capability for microstructure analysis in biological tissues.
• The derived analytical solution provides a robust framework for interpreting photoacoustic signals.
• PASA holds promise for non-invasive characterization of tissue microstructures.