Study for quantitative evaluation of photoaging with photoacoustic microscopy

Skin aging caused by ultraviolet light exposure is one of the serious problems from the viewpoint of beauty and healthcare. This is because ultraviolet light can cause age spot, wrinkles, at the worst case, skin cancer and so on. To evaluate skin aging, various modalities are being used, such as histopathological diagnosis, optical coherence tomography, ultrasound examination (B-mode imaging). However, they have disadvantages in terms of invasiveness, penetration depth and tissue specificity, respectively. To overcome these defects, photoacoustic imaging (PAI), a novel modality was used in this work. This modality can sense differences of tissue characteristics non-invasively. In this experiment, human skin tissues in various generations (i.e. various degrees of photoaging) were measured by using acoustic resolution photoacoustic microscopy (AR-PAM). To verify the feasibility of quantitative skin aging evaluation with PA technique, signals from sectioned human skin (cheek and buttock; female from 28 to 95 years old) were measured with PA microscopy. The effects of photoaging progress on the signal intensity were investigated. The results demonstrated that the PA signal from the dermis significantly increases with aging progress (p < 0.05). These analyses demonstrate the feasibility of quantitative skin aging evaluation with a PAI system.