Hepatic Fibrosis Assessment Using Fractal Analysis as a Histological Grading Method

Abstract

The histopathologic examination of hepatic fibrosis remains the gold standard in routine diagnosis of hepatopathies in veterinary medicine. However, the visual evaluation of fibrosis is usually limited by the observer’s capabilities. This paper aimed to present the applicability of fractal analysis as a quantitative method for evaluating the liver fibrosis grading using accessible tools, compared to one of the semiquantitative methods used currently in human histopathology, the METAVIR scoring system. Ovine liver histological sections taken from 22 slaughtered lambs, Masson’s trichrome-stained, were analyzed using the METAVIR score as the semiquantitative method for staging the liver fibrosis and inflammatory reaction, and the fractal dimension of collagen regions as a quantitative method for fibrosis evaluation. The results show strong correlations between fibrosis and fractal dimension as the statistics revealed that there is a significant difference between the presence of fibrosis and its absence (p<0.001). Significant differences between the fractal dimensions corresponding to F1 and F2 fibrosis grades were observed for the images aquired with objective lens 20A—. The presence of inflammatory cells did not influenced the fractal dimension of fibrosis. The Receiver Operating Characteristic (ROC) plot provided fair results for discriminating F1 versus F2 fibrosis grades, with the area under the ROC curve of 0.79. The study showed significant differences between the fractal dimension values of the liver tissue with different fibrosis grades, therefore, the fractal analysis provides a useful complementary tool in the histological examination. Â