In recent years, high-frequency ultrasound has become a new non-invasive tool for the diagnosis of skin diseases, aesthetic medicine and preoperative and postoperative evaluation due to its higher resolution. The purpose of this multi-center Study is to establish the normal reference values of skin thickness and blood flow parameters by high-frequency ultrasound in Chinese Han adults, and to explore the influencing factors, so as to provide quantitative reference for the evaluation of facial skin aging degree and cosmetic treatment.

The skin is the body's largest organ and acts as a protective, permeable barrier against pathogen invasion and against chemical and physical attacks. Long-term exposure to solar ultraviolet radiation is a major factor in exogenous skin aging. With the gradual improvement of living standards and the development of medical cosmetology technology, Chinese consumers have gradually increased their acceptance of cosmetology consumption. Facial skin, as one of the important indicators of "beauty", has obviously received the attention of cosmetic surgeons and dermatologists. Skin thickness is one of the important indicators of facial aging. However, different gender, different parts of the skin thickness is very different, especially the facial skin, the thickness of the epidermis, dermis is different, and the facial plastic surgery, injection treatment, photoelectric treatment has a close relationship. In addition, the dermis is rich in blood vessels, especially in its deep layers, which play an important role in the nutritional support of tissues and homeostasis of the internal environment. With the increase of age, the degree of dermal vascularization decreases, which is also one of the factors affecting skin aging. Therefore, in aesthetic medicine, more accurate quantitative evaluation of skin thickness and blood flow rather than simple subjective evaluation is very important.

Ultrasound is a non-invasive imaging technique widely used in clinic. In recent years, with the development of ultrasound technology, the frequency of ultrasonic probes has been increasing. Because of its higher resolution, high-frequency ultrasound can clearly display the layer and structure of the skin, and achieve accurate measurement of skin thickness and evaluation of dermal blood flow. High-frequency ultrasound has become a new non-invasive tool for the diagnosis of skin diseases, aesthetic medicine and preoperative and postoperative evaluation. The purpose of this multi-center Study is to establish the normal reference values of skin thickness and blood flow parameters by high-frequency ultrasound in Chinese Han adults, and to explore the influencing factors, so as to provide quantitative reference for the evaluation of facial skin aging degree and cosmetic treatment.

Inclusion Criteria:

1. Han nationality;
2. Ages 18-79;
3. Normal blood pressure (139-90/89-60mmHg);
4. Body mass index < 30 kg/m2;
5. Blood routine, fasting blood glucose, blood lipid, liver and kidney function, electrocardiogram were normal;
6. No history of skin disease, connective tissue disease, cardiovascular disease, diabetes, severe liver and kidney dysfunction.
7. No history of drug use affecting cardiovascular system.

Exclusion Criteria:

1. People with skin diseases (such as eczema, psoriasis, scleroderma, etc.);
2. Any skin disease at the test site (such as dermatitis, acne, breakages, previous skin lesions, etc.);
3. chronic systemic diseases;
4. Use corticosteroid drugs or immunosuppressants;
5. Pregnant or lactating women;
6. People who have been exposed to ultraviolet radiation for a long time or have a history of sun exposure within 3 months;
7. The examined skin area has been previously treated with other methods;
8. Unable to cooperate with the inspector.

Chinese healthy Han adults