The effects of female skin aging on the statistics of backscattered envelope in high-frequency ultrasound

Skin aging is a step-by-step and continuous process. It is vital to undertake accurate quantitative assessments of the skin rather than relying solely on subjective judgments. High-frequency ultrasound provides high-resolution imaging of the superficial skin layers, and its echo signals reflect the microstructure of the skin. To date, it has not been reported that statistically analyze the backscattered signal envelopes of skin tissue before and after aging. In our research, we investigated the impact of skin aging on the fitting performances of the Generalized Gamma (GG) K, Nakagami and Weibull distributions for the modeling effectiveness of empirical probability density histograms (EPDHs) of echo envelopes for in the upper dermis of facial skin from women of different ages, using the Kolmogorov-Smirnov (KS) statistic as a measure of goodness-of-fit. All distribution parameters were obtained using the maximum likelihood method. The results indicate that, compared to younger skin, the envelope statistics of aged skin exhibit a stronger tendency toward a Pre-Rayleigh distribution. Skin aging affects the fitting performance of the distributions. The GG distribution with two shape parameters is least affected compared to the other three distributions.