The Enhancement of Confocal Images of Tissues at Bulk Optical Immersion

TL;DR

This study theoretically and experimentally investigates how glycerol-induced dehydration enhances confocal imaging depth in skin tissues by reducing scattering, thus improving image contrast and resolution for deeper tissue visualization.

Contribution

It introduces a semi-infinite multilayer Monte Carlo model to predict optical improvements in skin imaging due to glycerol application, combining theory with in vitro experiments.

Findings

Glycerol reduces skin scattering, increasing imaging depth.

Confocal imaging can monitor deeper dermal layers during tissue clearing.

Simulation results align with experimental measurements.

Abstract

The purpose of the present work is a theoretical examination of how localized skin-tissue dehydration affects the depth of the confocal probing and what depth of effective detection can be reached with the chemical administration of skin tissues. A semi-infinite multilayer Monte Carlo model is used to estimate spatial localization of the output signal offered by a confocal probe. A solution of glycerol is taken in the capacity of innocuous osmotic agent. Diffusion of this bio-compatible chemical agent into the skin temporarily pushes water out of the tissues and results in the matching of the refractive indices of skin structural elements. This temporarily decreases scattering and increases transparency of topical skin layers, which allows for unrestricted light to permeate deeper into the skin. The results of simulation show that signal spatial localization offered by a confocal probe in the skin tissues during their clearing is usable for the monitoring of deep reticular dermis and improving the image contrast and spatial resolution. A discussion of the optical properties of skin tissues and their changes due to diffusion of glycerol into the skin is given. Optical properties of tissues and their changes due to chemical administration are estimated based on the results of experimental in vitro study with rat and human skin.