j. Soc, Cosmet, Chem,, 48, 243-251 (September/October 1997) Epidermal echoDenicity as a hydration parameter: The effect of moisturizers on the skin as evaluated by 20 MHz B-scanninD GIOVANNI PELLACANI, MARIANGELA FRANCOMANO, GIULIA GIUSTI, and STEFANIA SEIDENARI, Department of Dermatology, University of Modena, via Del Pozzo 71, 41100 Modena, Italy. Accepted for publication October 31, 1997. Synopsis Hydration of the stratum corneum after a short-term application of three skin-care products (petrolatum and two different moisturizers) was studied on the forearms of 15 healthy volunteers. Non-invasive methods were used. Evaporimetry, corneometry and B-scanning were carried out at the beginning, immediately after removal of the test chamber, and 15, 30, 60, 120, and 180 minutes later. Echographic recordings were performed by 20 MHz B-scanning and processed by a dedicated software (Dermavision 2D, Cortex Tech- nology, Hadsund, Denmark) based on the selection of amplitudes of interest and segmentation procedures. Segmentation of the images was performed employing two amplitude intervals, respectively highlighting hyper-reflecting (epidermis, lower part of dermis) and hypo-echogenic parts of the tissue. The evaluation of the dermis showed an attenuation of the hyper-reflecting areas of the deep dermis for all three substances and a significant decrease in echogenicity for petrolatum alone. Superficial hyper-reflecting areas assessing epidermis were significantly reduced in respect to baseline, at all assessment times for all three products. This echographic aspect corresponded to increased capacitance values, which were recorded for up to 180 minutes. In conclusion, 20 MHz B-scanning evaluation represents a valid support for the assessment of skin hydration. INTRODUCTION It is widely recognized that one of the most important skin problems encountered by consumers is skin dryness, which represents a spectrum of disorders ranging from a few uplifting flakes to conditions referred to as ichtyosis (1). Roughness, scaling, cracks, redness, and a feeling of tightness are skin features that are usually relieved by mois- turizers. Primary claim for the efficacy of skin-care products is hydration, clinically interpreted as the capacity to render the skin smoother and softer. However, little is known as yet about the physiological effects of moisturizers. Essentially two testing procedures are used to assess the effects of moisturizers on the hydration of the stratum corneum: long-term tests (2-4), which enable an evaluation obtained after ordinary use of the products, and short-term tests (5-12), which employ 243

244 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS a single application of moisturizers for up to three hours. With short-term test methods, incorrect use, bad compliance, and daily variations due to individual and environmental factors are easily controlled (10). In these studies transepidermal water loss (TEWL) and electrical capacitance (6,7,9,10) as hydration parameters are usually assessed. The quan- tiffcation of skin surface lipids (7,10), the evaluation of the mechanical properties of the skin (11), macrophotography and studies on skin replicas (5) are also employed to obtain further information on the possible role of moisturization on stratum corneum functions and biophysical properties. The aim of our study was to investigate the ultrasonographic aspects of skin hydration and to correlate them to variations in TEWL and capacitance values, as induced by a single application of different moisturizers. PATIENTS AND METHODS EXPERIMENTAL DESIGN The study was carried out on 15 healthy volunteers, six males and nine females, aged 25 to 35. Subjects were asked to avoid using any skin-care product for two days before testing. Three areas on the volar aspect of the forearm, 3, 6, and 9 cm distal from the elbow crease, were studied. Three different formulations were tested: petrolatum and two commercial products, moisturizer 1 and moisturizer 2 (oil-in-water emulsions). Patch tests with 60 mg of each product were applied for one hour using large Finn- Chambers on Scanpor tape. Immediately after patch-test removal, product residues were gently removed by wiping the skin with gauze. Measurements were performed at the beginning of the experiment, immediately after removal of the test chamber, and 15, 30, 60, 120, and 180 minutes later, after a 30-minute acclimatation period in a room with temperature at 21-22øC and 40-50% humidity. INSTRUMENTS The hydration of the epidermis was assessed using the corneometer CM 820 (Courage+Khazaka, Germany), which measures the electrical capacitance of the skin surface, expressed in arbitrary units (a.u.). Values are displayed digitally. The probe consists of a 49-mm 2 glass surface, applied on the skin under a standard load of 3,65 N, kept constant by a spring. Each recorded value represents the mean value of three measurements. Transepidermal water loss (TEWL) was measured by an Evaporimeter EP1 (Servomed, Sweden). The hand-held probe measures atmospheric temperature and dampness at two points, 3 and 6 mm above skin surface evaporation is calculated from the detected water gradient. Measurements were taken according to the guidelines of the Standardization Group of the European Society of Contact Dermatitis (13). Echographic evaluations were carried out by a 20 MHz B-scanner (Dermascan C, Cortex Technology, Denmark), which produces images representing a cross section of the skin. Dermascan C is provided with a 20 MHz transducer, which enables the high-definition study of tissues close to the body surface.