Magnetic resonance imaging showed that the 3D architecture of fibrous septae couldn't be modelled simply as perpendicular planes for women and tilted planes at 45 degrees for men. MR spectroscopy did not confirm the hypothesis of increased water content in the adipose tissue of women with cellulite as suggested by others, except if such water would be located in the connective septae.
Sonoelastography and transient elastography are two ultrasound-based techniques that facilitate noninvasive characterization of the viscoelastic properties of soft tissues by investigating their response to shear mechanical excitation. Young's modulus is the principle assessment parameter. Because it defines local tissue stiffness, it is of major interest for the medical imaging and cosmetic industries as it could replace subjective palpation by yielding local, quantitative information. In this paper, we describe a new high-resolution device capable of measuring local Young's modulus in very thin layers (1-5 mm) and devoted to the in vivo evaluation of the elastic properties of human skin. It uses an ultrasonic probe (50 MHz) for tracking the displacements induced by a 300 Hz shear wave generated by a ring surrounding the transducer. The displacements are measured using a conventional cross-correlation technique between successive ultrasonic back-scattered echoes. First, this noninvasive technique has been experimentally proven to be accurate for investigating elasticity in different skinmimicking phantoms. Second, data were acquired in vivo on human forearms. As expected, Young's modulus was found to be higher in the dermis than in the hypodermis and other soft tissues.
Objective
To explore the relationship between skin surface hydration and Trans‐Epidermal Water Loss (TEWL) when simultaneously measured.
Methods
Six circular skin areas of the forearms (3 per forearm, 3 cm in diameter) of 12 Caucasian women were used as models. 4 prototypes of formulae of different compositions containing glycerol at different concentrations 7%, 10% and 40% were used as models of hydrating products. One formula (glycerol‐free) was used as control vehicle. Standardized applications of formulae (2 mg/cm2) were performed on 5 skin sites chosen at random, the other being left as bare/control. A recently marketed instrumental device that records the skin surface hydration and TEWL on a small skin area in a simultaneous manner was used. Measurements were carried out at T0 (pre‐application), at 1 h (T1) and 5 h (T5) post applications on two close sites within the 6 defined areas of both forearms.
Results
The new instrumental device allowed to clearly differentiate the 5 formulae (i.e. 7% vs. 10%) with regard the dose effect brought by glycerol (7%, 10%, 40%) and to record their lingering effects at T1 and T5. Both parameters were found significantly and negatively correlated, i.e. the higher the skin hydration, the lower the TEWL. The 40% concentration of glycerol, that leads to the highest skin hydration, brings a drop in the TEWL by about a two‐fold factor. Skin hydration of bare skin and control/vehicle sites showed minor and non‐significant changes along 5 h. Instead, the control/ vehicle slowed down the TEWL to a slight extent.
Conclusion
The use of this new instrumental device shed a new light on the mutual and inverse relationships between skin hydration and TEWL. Results suggest that, at high concentration, glycerol leads to largely increase the water content of both epidermal and dermal compartments, possibly leading to structural changes in the skin relief.
With ageing, some few functional and structural changes are observed in the scalp of Caucasian women. Similarities or differences with those previously reported in other skin sites are discussed.
Background: Aging signs are much visible on the surface of the skin that presents different changes: cheeks start to sag, more and deeper wrinkles appear, and pigmentation spots increase. Face diagnostic to recommend products includes assessing cutaneous micro-relief or the micro-depressive network on the face. Furthermore, there is an increasing demand for clinical and instrumental methods to prove the efficacy of anti-aging treatments. As a result, very accurate and sensitive three-dimensional (3D) devices are developed and validated to measure and quantify aging skin and to catch fine anti-aging products acting on wrinkles and fine lines.Methods: AEVA-HE, a non-invasive 3D method based on fringe projection technology, is used to robustly characterize the skin micro-relief from a full-face acquisition and from multiple extracted zones of interest. In vitro and in vivo studies are conducted to assess the reproducibility of this system and its precision toward a standard fringe projection system, DermaTOP.
Results:The AEVA-HE successfully measured micro-relief and wrinkles and demonstrated the reproducibility of measurements. AEVA-HE parameters were found highly correlated to DermaTOP.
Conclusion:The present work illustrates the performance of the AEVA-HE device and its dedicated software kit as a precious tool for quantifying the major characteristics of wrinkles appearing with age and thus offers a high potential for assessing the effect of anti-wrinkling products.
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