Method for depth-resolved quantitation of optical properties in layered media using spatially modulated quantitative...

Area of Science:

• Biomedical Optics
• Spectroscopy
• Photonic Imaging

Background:

• Quantitative spectroscopy techniques often rely on homogeneous tissue models.
• Biological tissues like skin possess complex layered structures, challenging existing spectroscopic methods.
• Accurate optical property extraction from skin is crucial for various diagnostic and therapeutic applications.

Purpose of the Study:

• To develop and validate a depth-resolved optical property quantitation method for layered biological tissues.
• To adapt spatially modulated quantitative spectroscopy (SMoQS) for analyzing skin's optical properties.
• To assess the accuracy of SMoQS in determining layer-specific optical properties and chromophore concentrations in a two-layer model.

Main Methods:

• Development of a two-layer model for depth-resolved optical property analysis.
• Utilized Layered Monte Carlo simulations to model light propagation in layered media.
• Employed layered tissue-simulating phantoms for experimental validation of the SMoQS method.

Main Results:

• The empirical SMoQS method accurately determined top layer thickness in phantoms within tens of microns.
• Layer-specific chromophore concentrations were quantified with an average accuracy of <±10%.
• Bulk spectroscopic quantitation significantly underestimated layer-specific chromophore concentrations and was confounded by top layer thickness.

Conclusions:

• The developed two-layer SMoQS method enables accurate depth-resolved optical property quantitation in layered media.
• This approach overcomes limitations of homogeneous models for analyzing skin's optical properties.
• SMoQS offers a significant improvement over bulk spectroscopic methods for characterizing layered biological tissues.