Layer-based, depth-resolved computation of attenuation coefficients and backscattering fractions in tissue using...

Area of Science:

• Biomedical Optics
• Medical Imaging
• Optical Physics

Background:

• Optical coherence tomography (OCT) offers structural imaging but requires enhanced functionalization for quantitative interpretation.
• The OCT attenuation coefficient (µ) provides functional contrast, relating to sub-resolution tissue properties.
• Existing methods for calculating µ sacrifice axial information or assume constant backscattering fraction, limiting accuracy in layered tissues.

Purpose of the Study:

• To develop a novel method for depth-resolved attenuation coefficient measurement in OCT that removes the dependence on backscattering fraction.
• To enable accurate quantitative analysis of layered tissues by analyzing signal within discrete layers.
• To provide complementary layer-resolved backscattering fraction data for enhanced diagnostic capabilities.

Main Methods:

• Developed a signal analysis technique operating within discrete tissue layers to overcome limitations of previous methods.
• Implemented automated layer detection for validation in layered phantoms.
• Validated the approach using Mie theory for theoretical property calculations and preliminary tissue imaging with histological correlation.

Main Results:

• The new method preserves full depth resolution of the attenuation map while eliminating the constant backscattering fraction assumption.
• Measured optical properties in layered phantoms showed good agreement with theoretical values.
• Preliminary tissue results demonstrated the feasibility of layer-resolved analysis and provided complementary scattering information.

Conclusions:

• The improved depth-resolved attenuation coefficient measurement, combined with layer-resolved backscattering fraction, enhances quantitative OCT imaging.
• This approach overcomes previous constraints, enabling more accurate estimation of particle density and size.
• The enhanced diagnostic power of quantitative OCT imaging is expected to improve clinical applications.