Confocal Raman spectroscopy: in vivo measurement of physiological skin parameters—a pilot study

Publication date: Available online 10 August 2017
Source:Journal of Dermatological Science
Author(s): Lisa Binder, Safoura Sheikh Rezaei, Andreas Baierl, Lukas Gruber, Michael Wolzt, Claudia Valenta
BackgroundIn vivo application of confocal Raman spectroscopy (CRS) allows non-invasive depth measurement of the skin. Thereby obtained knowledge of the skin composition is essential to reliably assess the actual skin state. Besides other components, the skin cholesterol concentration is of interest; however, little is known about its connection to the cholesterol concentration quantified in venous blood.ObjectiveIn this study, the skin composition of the volar forearm was characterised in vivo using CRS. In particular, the potential of CRS as a non-invasive method to determine cholesterol levels was validated.MethodsRaman spectra of the volar forearm of 15 participants were recorded twice within two weeks. Depth concentration profiles for major skin components were generated. Stratum corneum (SC) thickness was calculated from water concentration profiles. In order to examine the usability of dermal CRS for cholesterol level determination, results were compared to fasting total cholesterol values in venous blood as determined by an enzymatic method.ResultsDepth concentration profiles for the skin components of interest showed a comparable curve progression for the participants. It was possible to link changes in concentration to physiological processes. Moreover, age-related differences could be found. Several novel mathematical approaches for the comparison of the skin cholesterol content and the blood cholesterol concentration have been developed. However, no correlation passed the Bonferroni multiple testing correction.ConclusionCRS serves as useful tool for the in vivo monitoring of skin components and hydration. Concentration depth profiles provide information about the current skin condition. No distinct correlation between the skin and blood cholesterol concentration was found within the scope of the present study. Concerning this matter, the heterogeneous distribution of cholesterol in the skin may be a factor influencing these results.



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