Optimized phase gradient measurements and phase-amplitude interplay in optical coherence elastography.

Area of Science:

• Biomedical Optics
• Medical Imaging
• Tissue Mechanics

Background:

• Compressional optical coherence elastography (OCE) estimates tissue strain using phase-variation gradients from OCT scans.
• Current methods are limited to small strains (<10⁻⁴ to 10⁻³) due to noise and phase-unwrapping challenges.

Purpose of the Study:

• To extend OCE methodology for increased accuracy and strain range.
• To address artifact formation and improve phase-gradient estimation techniques.

Main Methods:

• Investigated the impact of higher strains (order of magnitude greater) on phase-gradient difference accuracy.
• Analyzed amplitude-phase interplay to understand artifactual stiff inclusions.
• Developed and evaluated novel phase-gradient estimation methods beyond least-squares fitting.

Main Results:

• Higher strains significantly improve accuracy, bypass phase-unwrapping, and minimize decorrelation noise.
• Artifactual stiff inclusions near bright scatterers were explained by amplitude-phase interplay.
• Proposed gradient estimation methods demonstrated superior performance compared to conventional techniques.

Conclusions:

• Optimized phase-variation methodology in OCE allows for more accurate and robust strain estimation across a wider range.
• The findings offer improved methods for characterizing tissue mechanical properties using OCT elastography.