Robust Photoacoustic Eigen Waveform Analysis for Characterization of Cancellous Bone

Area of Science:

• Biomedical Imaging
• Biophotonics
• Medical Physics

Background:

• Photoacoustic (PA) imaging offers rich microstructure data for disease diagnosis and therapy monitoring.
• Imaging bone tissue with PA is difficult due to bone's high scattering and attenuation.
• PA signal waveforms contain optical and ultrasonic properties indicative of bone health.

Purpose of the Study:

• Develop a robust, compensation-free PA eigen waveform analysis (PEWA) method.
• Characterize high-scattering cancellous bone using transmission mode PA imaging.
• Quantify bone health parameters from PA signals.

Main Methods:

• Conducted numerical simulations and experimental studies on cancellous bone models with varying bone mineral densities (BMDs) and optical/ultrasonic properties.
• Analyzed PA signals using the PEWA method to quantify parameters like the exponential growth coefficient.
• Validated the method on ex vivo animal cancellous bone tissues.

Main Results:

• Lower BMDs correlated with lower exponential growth coefficients in simulations.
• The exponential growth coefficient demonstrated superior robustness and stability compared to amplitude-based parameters.
• Experimental results on ex vivo bone tissues validated simulation findings, confirming PEWA's ability to assess BMD.

Conclusions:

• The compensation-free PEWA method is nonionizing, noninvasive, and penetrates both bone matrix and marrow.
• This technique holds potential for early and rapid clinical assessment of osteoporosis.
• The PEWA approach is applicable to miniaturized equipment for intelligent bone health evaluation.