Image processing techniques for quantitative analysis of skin structures.

Computer-based image processing and analysis techniques were developed for quantitative analysis of skin structures in color histological sections. Performance was compared with traditional non-image processing counting methods. Skin sections were stained with Masson's trichrome, hematoxylin and eosin, picrosirius red, or one of several elastin stains. The image processing software identified the top of the cellular epidermis and the dermal-epidermal junction and then calculated the volume of the cellular layer of the epidermis, epidermal thickness, and the ratio of the dermal-epidermal junction surface area to the in-plane surface area. It also identified cells and collagen and calculated cellular densities and collagen densities in the papillary and reticular layers of the dermis. Attempts to computationally process elastin-stained sections to determine elastin density were unsuccessful. The described techniques were used in a preliminary study to compare mechanically stressed skin with control skin. Results showed significant differences in cellular density in the papillary dermis and collagen density in the reticular dermis for skin subjected to combined shear/compression or tension compared with an unstressed control. Measurements made with the computer technique and traditional technique showed comparable results; the mean difference in measurements for epidermal features was 5.33% while for dermal features it was 2.76%. Significance testing between control and experimental groups showed similar results, though for three of the 28 comparisons the computer method identified a significant difference while the traditional method did not. The computer method took longer to conduct than the traditional method, though with recent advances in computer hardware this time difference would be eliminated.