Quantitative description of echographic images of morphea plaques as assessed by computerized image analysis on 20 MHz B-scan recordings.

Abstract

In order to find image descriptors enabling the characterization of sclerotic skin of morphea plaques and their objective differentiation from normal skin, we studied 52 lesions in 35 patients affected by plaque type morphea. Echographic evaluations were carried out using a 20 MHz B-scanner, providing cross-sectional images of the skin. Images were processed by a program providing a numerical representation of the picture data, based on the following parameters, which were considered for 7 different amplitude intervals: 1) the extension of image areas marked by amplitude bands of interest, 2) the percentage of the image surface reflecting within a homogeneous amplitude band, 3) the number of objects composing the image, 4) the average object size, and 5) the "density" of the objects. For all parameters considered, marked differences between sclerotic skin and normal tissue were observable. When assessment is performed with amplitude bands covering the lower part of the scale, the image referring to sclerotic tissue appears relatively homogeneous with few, large objects within a thickened skin block, which occupy a more extended image surface in comparison to images of normal skin, characterized by spots, which are small and closely packed. On the contrary, binary images of morphea plaques transformed by intermediate to high amplitude intervals appear with fewer objects of approximately the same size or smaller, which are less compressed in respect to healthy skin images.