Visualizing kinetics of diffusional penetration in tissues using OCT-based strain imaging

Area of Science:

• Biomedical Optics
• Biophysics
• Tissue Mechanics

Background:

• Optical Coherence Elastography (OCE) is a novel technique for visualizing tissue mechanical properties.
• Understanding solute diffusion in tissues is crucial for drug delivery and optical imaging.
• Osmotic strains significantly impact tissue structure and optical properties.

Purpose of the Study:

• To introduce and validate a new application of OCE for quantitatively analyzing osmotic strain kinetics.
• To investigate the diffusion dynamics of osmotically active solutions in biological tissues.
• To correlate OCE-visualized strain dynamics with Fick's theory of diffusion.

Main Methods:

• Utilized Optical Coherence Elastography (OCE) to capture spatio-temporal osmotic strain dynamics.
• Applied various osmotically active solutions with controlled concentrations.
• Performed theoretical interpretations and numerical simulations to analyze diffusion processes.
• Validated OCE findings against Fick's theory and literature data.

Main Results:

• OCE successfully visualized osmotic strain kinetics, ranging from fractions of a percent to tens of percent.
• The visualized dynamics accurately reflected osmotic dehydration and solute penetration rates.
• OCE-derived diffusivity coefficients were consistent with established literature values.
• Experimental examples, theoretical interpretations, and simulations supported the findings.

Conclusions:

• OCE provides a quantitative method to study the kinetics of osmotic strains in biological tissues.
• The technique effectively visualizes and quantifies solute diffusion, aligning with Fick's theory.
• OCE has broad applications in studying the diffusion of various osmotically active substances, including drugs and optical clearing agents.