Evaluation of skin viscoelasticity and anisotropy by measurement of speed of shear wave propagation with viscoelasticity skin analyzer

Skin viscoelasticity was evaluated by a fast, noninvasive assay based on th e measurement of the speed of elastic shear wave propagation in the skin by a new portable and user-friendly viscoelasticity skin analyzer. The range of speed of elastic shear wave propagation measured by viscoelasticity skin analyzer allows the evaluation of the stiffness of a wide spectrum of arti ficial materials as well as the viscoelasticity of skin of laboratory anima ls and human subjects. The directional nature of the measurement enables to monitor the anisotropy of the materials tested. The speed of elastic shear wave propagation was shown to have a positive correlation with the stiffne ss of the material tested. In symmetric contralateral areas of intact skin in rabbit ears, similar viscoelasticity and anisotropy were observed. Twent y-four hours after the induction of local edema by croton oil, skin stiffne ss and anisotropy were significantly increased. In healthy human subjects o f both sexes significant variations in skin stiffness and anisotropy were o bserved in three different skin areas along the forearms, but the speed of elastic shear wave propagation was similar in the symmetric contralateral a reas. Age (17-65 y) seemed to have a limited effect on the viscoelasticity of the forearm skin. Hydrating creams decreased the stiffness of the forear m skin for only approximate to 3 h. The stiffness and anisotropy of the ski n of the breasts in female volunteers (20-86 y) increased with age, but the speed of elastic shear wave propagation was similar in symmetric contralat eral areas in the same individuals. Based on these results, we propose the application of the viscoelasticity skin analyzer in experimental and clinic al practice for quantitative evaluation of skin condition.