Abstract: 【Abstract】    Objective    To measure the thickness and echo density of the skin at multiple sites of healthy adults by using high-frequency ultrasound. Methods    A total of 50 healthy volunteers were enrolled from Department of Dermatology and Venereology, China-Japan Friendship Hospital between June and December in 2018, including 33 females and 17 males aged 22 - 69 years. The thickness and echo density of the epidermis, dermis and epidermis-dermis layer were detected by using high-frequency ultrasound at 12 sites, including the forehead, cheek, chest, abdomen, and the inner and outer sides of the upper arm, forearm, thigh and leg. The means of two groups were compared by using t test, and means of several groups were compared by using one-way analysis of variation. Results    High-frequency skin ultrasound images differed among different anatomical sites. There were significant differences in the thickness and echo density of the epidermis, dermis and epidermis-dermis layer among the 12 sites （P < 0.05）. The epidermis was thickest at the inner side of the thigh （160.68 μm ± 25.71 μm）, the dermis was thickest at the cheek（1 828.78 μm ± 399.10 μm）, and the epidermis-dermis layer was thickest at the cheek（1 943.48 μm ± 402.4 μm）. The echo density of the epidermis, dermis and epidermis-dermis layer was highest at the inner side of the leg （152.27 ± 21.56）, forearm （52.71 ± 15.57） and forearm （62.56 ± 15.76） respectively. The thickness of the epidermis, dermis and epidermis-dermis layer at the forehead, cheek and the inner side of the forearm was significantly higher in male volunteers than in female volunteers （P ≤ 0.05 or < 0.01）, while the echo density of the dermis and epidermis-dermis layer at the forehead, cheek and the outer side of the leg was significantly lower in male volunteers than in female volunteers （P < 0.05 or 0.01）. Conclusion    Differences exist in skin thickness and echo density among different anato mical sites and between male and female healthy adults.

Key words: Ultrasonography, Epidermis, Dermis, Skin thickness, Skin echo density