DIGITAL IMAGE-ANALYSIS (DIA) OF COLOR CHANGES IN HUMAN SKIN EXPOSED TO STANDARDIZED THERMAL-INJURY AND COMPARISON WITH LASER-DOPPLER MEASUREMENTS

Clinical macrophotography followed by digitization and computer-assist ed image analysis was performed on volunteers exposed to a mild experi mental thermal injury. The aim was to elaborate a non-invasive techniq ue allowing repetitive and quantitative monitoring of induced erythema and to evaluate a possible relationship with laser Doppler measuremen t of skin perfusion. A standardized 1 x 1 cm large thermal trauma was induced in the skin of the ventral forearm of 12 volunteers. Photograp hic recordings and skin blood flow measurements were made preburn and at 30-min, 1-h, 2-h, 4-h and 12-h postburn. Image analysis was perform ed with two colour systems, normalized rgb-values (rgb) and Hue-Satura tion-Intensity (HSI). Erythema measured by rgb and HSI was most pronou nced during the first hour postburn, after which it gradually decrease d in order to increase again at 12 h postburn. Skin perfusion peaked a t 30 min postburn and then continuously decreased during the course of the experiments. Degree of erythema could be quantified using both co lour systems and a linear relationship was obtained between the observ ed colour changes of both systems and changes in skin perfusion. Resul ts may also indicate that erythema can be present without a concomitan t increase in skin perfusion, probably representing postburn venous st asis. The present study showed that digital image analysis is a non-in vasive technique allowing repetitive and quantitative analysis of skin erythema which can be used to monitor pathophysiological changes in t he body as well as the result of their treatment.