Mechanical spectroscopy and imaging of skin components in vivo: Assignment of the observed moduli

Background: The need to quantitatively identify the composition and organization of the macromolecular components of skin, skin lesions, scars, tumors, extracellular matrices (ECMs), and wound tissue has been a goal of researchers for many decades. A variety of studies have been recently reported applying optical coherence tomography (OCT) to image skin and cutaneous lesions. Materials and Methods: This article describes the use of vibrational OCT to image and noninvasively characterize the macromolecular components of the ECM of skin. Results: We report that the major macromolecular components of skin and scar can be identified noninvasively by their characteristic moduli calculated from measurements of the resonant frequency and tissue thickness. Moduli for fat (0.03 MPa), elastic tissue (0.8 MPa), skin (2 MPa), and scar (7 MPa) can be differentiated using images and measurements of the resonant frequency and the sample thickness obtained from OCT. Conclusions: Using vibrational OCT, it is possible to identify and map the location of the macromolecular components in skin and skin lesions.