Non-invasive evaluation techniques to quantify the efficacy of cosmetic anti-cellulite products

The majority of women suffer from the unattractive sight of dimpling skin on the thighs and buttocks, globally known as cellulite. Cellulite can be regarded as the most investigated non-disease, because, from the cosmetic viewpoint, most women desire a reduction in cellulite severity. Despite investigations made, cellulite is still not well understood at the cellular level, which leads to controversy regarding the investigative methods for cellulite reduction as well as the development of products to treat cellulite skin.

The aim of our work was to improve the set up of macrophotography for making images of dimpled skin and to automatize image analysis of 20 MHz ultrasound imaging - these two methods being just two of a variety of available methods for investigating cellulite skin.

Macrophotography was standardized on the aspects of volunteer's positioning, skin illumination, background used, and camera position. It was performed before, during and after a 3-month-treatment of a cosmetic product. Scoring assessments of the generated images were made by the volunteers themselves as well as by six trained experts. Ultrasound imaging was performed at the baseline visit in order to correlate the newly developed analysis with the visually rated cellulite score. A second study is also presented showing a variety of parameters that can be used for cosmetic testing of cellulite products: skin firmness, blood circulation and circumferential thigh measurements.

Standardization of macrophotography minimized differences in image features between assessment times, therefore, enabling follow-up rating assessments of the images. A custom-made rating program simplified the scoring procedure by presenting images as blind and randomized, and by implementing computer-based analysis using an online rating scale. Volunteers and experts scored significant improvement of skin appearance over the course of a 3-month cosmetic treatment. Image analysis of ultrasound imaging was automatized, and a modification of the commonly known roughness parameter Ra was implemented to characterize cellulite severity. Comparison with the visually rated cellulite score showed an existing correlation between the score and the modified parameter Ra(m). Further parameters investigated in an exemplary study, as mentioned above, demonstrated a significant improvement of skin appearance after treatment with a cosmetic product.

Macrophotography and ultrasound imaging can be regarded as important tools for determining and quantifying the aspects of cellulite. With a gold standard missing for investigating cellulite severity, these two methods may not determine cellulite at the cellular level, but they do characterize the skin appearance so typical for cellulite. Combined with a variety of other methods, macrophotography and ultrasound imaging can very well define cellulite-reducing efficacy from the cosmetic point of view.