Quantitative analysis of age-related changes in vascular structure, oxygen saturation, and epidermal melanin structure using photoacoustic methods

Abstract

Background: Vascular structure, blood oxygen saturation, and melanin status of the epidermis are chromophore factors related to light absorption. Therefore, they are likely to be related to skin appearance. Thus, it is important to measure these internal skin features and understand their characteristics. Thus, we aimed to analyze the individual differences and aging changes in the skin by measuring the internal skin characteristics, such as vascular structure, oxygen saturation, and the 3D distribution of melanin in the epidermis, using a noninvasive photoacoustic (PA) measurement method. Materials and Methods: A PA measurement device was used as a noninvasive measurement method. Eighty Japanese women aged between 20 and 60 years were enrolled. The target area was the buccal region of the face. Results: The blood vessel structure showed a decrease in fine vessels with age, with a stronger tendency observed in the dermis layer, and the volume of blood vessels was larger in the dermis layer than in the dermal–subcutaneous fat boundary layer. Oxygen saturation showed a similar decreasing trend with age in all depths examined. Melanin condition as the torus-like pattern structure tended to increase with age. Conclusion: PA measurements revealed the characteristics of several chromophores, providing a new skin aging mechanism.