Nonـinvasive evaluation of elasticity of skin with the processing of ultrasound images during ultraviolet radiation: An animal photoaging model.

OBJECTIVE The aim of this study was to provide a non-invasive imaging method to evaluate the physical and mechanical parameters as a novelty method during skin photoaging. METHODS In order to evaluate the process of skin damage, 25 mice (C57BL6) were exposed to UVB radiation (0.03 mW/cm2 ), 5 times a week for 5 weeks. The thickness of the epidermal and dermal layers was measured weekly from the ultrasound images (40 MHz). The elastic parameters of the skin were estimated from the processing of the sequential ultrasound images with the motion detection algorithm during the injury generation process. RESULTS The thickening, Young modulus, and shear modulus of the dermal and epidermal layers during the UVB damage process significantly increased during the 5-week study period (p<0.05). In addition, the percentage of changes in the thickness of the epidermal layer (0.22 ± 0.01 mm in day 0 to 0.37 ± 0.02 mm in day 35) and dermal layer (0.57 ± 0.05 mm in day 0 to 0.90 ± 0.08 mm in day 35) increased by 68% and 57%, respectively. Furthermore, Young modulus (154.41 ± 8.8 kPa) was 11 times more than that of non-irradiated skin (14.90 ± 2.2 kPa) and the shear modulus (2.33 ± 0.04 kPa) was 2.2 times more than non-irradiated skin (1.06 ± 0.04 kPa). CONCLUSION With processing the sequential ultrasound images and extracting the thickening, the elasticity of the skin layers can detect skin lesions by UVB radiation.