Optical coherence tomography angiography offers comprehensive evaluation of skin optical clearing in vivo by quantifying optical properties and blood flow imaging simultaneously

Abstract

Tissue optical clearing (TOC) is helpful for reducing scattering and enhancing the penetration depth of light, and shows promising potential in optimizing optical imaging performances. A mixture of fructose with PEG- 400 and thiazone (FPT) is used as an optical clearing agent in mouse dorsal skin and evaluated with OCT angiography (Angio-OCT) by quantifying optical properties and blood flow imaging simultaneously. It is observed that FPT leads to an improved imaging performance for the deeper tissues. The imaging performance improve- ment is most likely caused by the FPT-induced dehydration of skin, and the reduction of scattering coefficient (more than ∼40.5%) and refractive-index mismatching (more than ∼25.3%) in the superficial (epidermal, dermal, and hypodermal) layers. A high correlation (up to ∼90%) between the relative changes in refractive-index mis- matching and Angio-OCT signal strength is measured. The optical clearing rate is ∼5.83 × 10−5 cm∕s. In addi- tion, Angio-OCT demonstrates enhanced performance in imaging cutaneous hemodynamics with satisfactory spatiotemporal resolution and contrast when combined with TOC, which exhibits a powerful practical application in studying microcirculation. ©