Qingming Luo

Skin backreflectance and microvascular system functioning at the action of osmotic agents

The in vivo back reflectance spectra of rat skin were measured by inter-dermal injection of glycerol and glucose solutions. The injection of glycerol solution caused a significant decrease in skin reflectance within the first few minutes, and the decreased reflectance was conserved for a long time period. The effect of glucose solution on skin optical clearing was also demonstrated. The decrease of reflectance was stronger than at glycerol injection but was conserved for a shorter period. For hyperosmotic solutions of glucose and glycerol the optical clearing of skin was coupled with stasis and dilation of microvessels in the area of application of the agent. To study the peculiarities of the blood microcirculation system the rat mesentery was used as an animal model. The effect of each agent on blood microcirculation had some distinctive features.

Controling the scattering of Intralipid by using optical clearing agents

Optical clearing agents (OCAs) with high refractive indices and hyperosmolarity can enhance the penetration of light in tissues by reducing scattering in tissues. However, the mechanism of tissue optical clearing is not much clear for the complex interaction between tissues and OCAs. In this work, Intralipid was mixed with different concentrations of OCAs, i.e. dimethyl sulfoxide (DMSO), glycerol, 1,4-butanediol, 1,2-propanediol, poly-ethylene glycol 200 (PEG200) and poly-ethylene glycol 400 (PEG400). Except for PEG200 and PEG400 that make aggregation of particles, the others kept the mixture uniform. The reduced scattering coefficients of uniform mixtures were predicted with Mie theory and measured by a commercially available spectrophotometer with an integrating sphere. The results show that all of the OCAs used enhance the optical clearing effect of Intralipid. If OCAs do not change the structure of Intralipid, Mie theory prediction matches well with the measurements. And the higher the refractive index of OCA, the smaller the reduced scattering coefficient. A simple formula deduced can quantitatively predict the optical clearing effect caused by OCAs. This work is helpful for clarifying the mechanism of tissue optical clearing, which will make the effect of optical clearing of tissue predictable and controllable.

Front Matter: volume 6534

This PDF file contains the front matter associated with SPIE Proceedings Volume 6534, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.This PDF file contains the front matter associated with SPIE Proceedings Volume 6534, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.