Improved quantification of collagen anisotropy with polarization-resolved second harmonic generation microscopy

Area of Science:

• Biomedical Optics
• Microscopy Techniques
• Biomolecular Imaging

Background:

• Label-free imaging of collagen organization is crucial for understanding tissue structure and disease.
• Polarization-resolved second harmonic generation (SHG) microscopy offers insights into collagen but lacks standardized methods for optimal laser polarization selection.
• Current approaches are limited in determining the best laser polarization for quantitative analysis of collagen anisotropy.

Purpose of the Study:

• To develop a novel methodology for selecting optimal laser beam polarization in SHG microscopy for tissue characterization.
• To establish a framework for accurate interpretation of SHG images and anisotropy maps for differentiating healthy and dysplastic tissues.
• To identify cancer signatures by analyzing collagen organization using optimized SHG parameters.

Main Methods:

• Implementing polarization-resolved second harmonic generation (SHG) microscopy.
• Calculating the anisotropy factor and collagen orientation index using Fast Fourier Transform (FFT) analysis.
• Developing a framework to select optimal laser beam polarization based on anisotropy and orientation index.

Main Results:

• The anisotropy factor shows similar polarization dependence to SHG intensity.
• A combined analysis of anisotropy factor and collagen orientation index provides a framework for optimal polarization selection.
• The developed methodology enables better differentiation between healthy and dysplastic tissue areas.

Conclusions:

• The novel methodology provides guidelines for selecting optimal laser polarization in SHG microscopy.
• This approach improves the quantitative analysis of collagen organization for disease detection.
• Optimized SHG imaging aids in distinguishing between healthy and cancerous tissue states.