Assessment of topical corticosteroid activity on experimentally induced contact dermatitis: echographic evaluation with binary transformation and image analysis.

A new echographic evaluation method employing a B scanner and a dedicated software (Dermavision 2D, Cortex Technology, Hadsund, Denmark) was used in assessing the potency of three different corticosteroids. Experimental lesions were induced by patch tests with nickel sulfate 5% in petrolatum in 10 sensitized subjects and treated with two medications of different steroids (clobetasol propionate, fluocinolone acetonide or clobetasone butyrate) performed 16 and 40 h after the application of the nickel patch tests. Clinical and echographic evaluations were carried out at the beginning of the experiment and 64 h after the induction of the reactions. After obtaining echographic images, these were processed by software, enabling the selection of amplitudes of interest, the highlighting of parts of images and their assessment by a value corresponding to the number of pixels (picture elements). For evaluations a low reflecting band was chosen, marking edema and inflammatory infiltration. At positive patch test sites we observed a progressive increase in the number of low reflecting pixels, in accordance with the intensity of the reaction. Therapeutic response was assessed as the difference between values of treated and untreated test sites. The rank order of the efficacy of test substances as determined echographically was identical to the rank order generally accepted for these steroids. This evaluation method of topical corticosteroid activity could be usefully employed besides traditional evaluation methods.