Characterization of in vivo human skin in response to mechanical indentation using optical coherence tomography
The biomechanical response of skin can reflect not only health or localized pathology, but also systemic disease or an abnormal physiological condition of an individual. Both the intrinsic stiffness of the solid constituents and the time-evolved redistribution of fluid within skin tissue can influence the biomechanical response to external forces. Therefore, it is important not only to evaluate the responding skin dynamics upon mechanical perturbation, but also to understand the intrinsic viscoelastic properties and fluid dynamics in the skin. While the clinical diagnosis of skin pathologies relies mostly on visual inspection and manual palpation, a more quantitative tissue characterization is highly desirable. Optical coherence tomography (OCT) is an interferometry-based imaging modality that offers an imaging resolution (cellular level) that surpasses those of most standard clinical imaging tools and has shown to be able suitable for in vivo skin imaging. Therefore, this thesis investigates OCT-guided characterization of the biomechanical response of skin, as well as the viscoelastic properties and the characteristics of local fluid transport. Quantitative analysis metrics were developed and demonstrated on in vivo human subjects, and a significant difference between the mechanically-perturbed and non-perturbed skins is revealed. Additionally, the quantitative results exhibit differences in the post-indentation scenarios between the young skin and the aged skin. Functional OCT techniques, such as optical coherence elastography (OCE) and Doppler OCT, are demonstrated to assess the stiffness and fluid dynamics of in vivo human tissue as well. The OCE results successfully reveal the stiffness at different anatomical sites, and the Doppler OCT shows the existence of the micro-vessels. This thesis research demonstrates the feasibility of quantitative skin characterization, the assessment of skin elasticity, and the revelation of fluid flows. With these information combined, a more objective and potentially more accurate diagnosis tool for skin pathologies may be possible in the future.
Dermatology, Fluid retention, Optical coherence tomography, Image characterization, Quantitative analysis, Biomechanical properties, Viscoelasticity, Fluid dynamics
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign