Measurements of the thermal coefficient of optical attenuation at different depth regions of in vivo human skins using optical coherence tomography: a pilot study.

Ya Su,X Steve Yao,Longzhi Wang,Zhihong Li,Zhuo Meng,Tiegen Liu

doi:10.1364/boe.6.000500

Abstract

We present detailed measurement results of optical attenuation's thermal coefficients (referenced to the temperature of the skin surface) in different depth regions of in vivo human forearm skins using optical coherence tomography (OCT). We first design a temperature control module with an integrated optical probe to precisely control the surface temperature of a section of human skin. We propose a method of using the correlation map to identify regions in the skin having strong correlations with the surface temperature of the skin and find that the attenuation coefficient in these regions closely follows the variation of the surface temperature without any hysteresis. We observe a negative thermal coefficient of attenuation in the epidermis. While in dermis, the slope signs of the thermal coefficient of attenuation are different at different depth regions for a particular subject, however, the depth regions with a positive (or negative) slope are different in different subjects. We further find that the magnitude of the thermal coefficient of attenuation coefficient is greater in epidermis than in dermis. We believe the knowledge of such thermal properties of skins is important for several noninvasive diagnostic applications, such as OCT glucose monitoring, and the method demonstrated in this paper is effective in studying the optical and biological properties in different regions of skin.

Highlights

Optical coherence tomography (OCT) is a noninvasive imaging technique that has been extensively used for study of the optical properties of superficial layers of biological tissues [1]
No detailed studies have been performed on the temperature-dependent attenuation or scattering coefficient of in vivo human skin in different layers, such studies may prove important for improving the accuracy and repeatability of OCT based noninvasive glucose monitoring
We have investigated the temperature dependence of optical attenuation coefficient of in vivo human skin with optical coherence tomography in this pilot study

Summary

Introduction

Optical coherence tomography (OCT) is a noninvasive imaging technique that has been extensively used for study of the optical properties of superficial layers of biological tissues [1]. Optical properties, such as the absorption coefficient ( μa ), (reduced) scattering coefficient ( μs ) and anisotropy factor that are dependent on the tissue state, can provide possibilities of improved non-invasive diagnosis. No detailed studies have been performed on the temperature-dependent attenuation or scattering coefficient of in vivo human skin in different layers, such studies may prove important for improving the accuracy and repeatability of OCT based noninvasive glucose monitoring. The detailed knowledge of the temperature dependencies of the attenuation coefficient ( μt ) in different depth regions of tissues may be valuable for other noninvasive diagnostic measurements [5,6,7,8]

Methods

Results

Conclusion