Objective evaluation of treatment effects on port-wine stains using L*a*b*color coordinates

Wide variations in port-wine stains and their responses to various therapie s pose a need for the development of an objective method to evaluate the ef fects of treatment. Several techniques such as laser Doppler, reflectance s pectrometry, and tristimulus colorimetry have been used to evaluate the col or of port-wine stains, but these techniques are limited by cost, small tes t size area, and other factors. Therefore, we developed a simple and cost-e ffective method of evaluating treatment results on port-wine stains using t he L*a*b* color coordinate system in combination with a personal computer. For 22 patients with port-wine stains, the slide photographs were digitized using a slide scanner. L*a*b* color differences of the normal control and port-wine stain sites were obtained before and after treatment, and treatme nt effect (percent) was calculated. By calculating each color difference be tween the lesion and normal skin both before and after treatment, problems arising from different illuminating conditions during photography were mini mized. The results were compared with the visual evaluation conducted by th ree experienced plastic surgeons. The treatment effects analyzed by L*a*b* color coordinate ranged from 4 to 95 percent, with a mean of 48.1 percent,w hereas treatment effects evaluated by the plastic surgeons ranged from 15 t o 92 percent, with a mean of 51.1 percent. The subjective clinical grades c orrelated well with the treatment effects obtained by the proposed color an alysis system (correlation coefficient, 0.89). The maximum difference in th e effect of treatment for a patient evaluated by the three clinicians was u p to 60 percent, which means that visual judgment is very subjective and va riable. The color analysis system proposed as a result of this study is ver y easy, objective, quantitative, cost-effective, and can be useful for the evaluation of treatment effects on colored skin lesions such as port-wine s tains.