Fractal analysis: An objective method for identifying atypical nuclei in dysplastic lesions of the cervix uteri

Objectives. Fractal geometry is a tool used to characterize irregularly sha ped and complex figures. It fan be used not only to generate biological str uctures (e.g, the human renal artery tree), but also to derive parameters s uch as the fractal dimension in order to quantify the shapes of structures. As such, it allows user-independent evaluation and does not rely on the ex perience level of the examiner. Methods. We applied a box-counting algorithm to determine the fractal dimen sion of atypical nuclei in dysplastic cervical epithelium. An automatic alg orithm, was used to determine the fractal dimension of nuclei in order to p revent errors from manual segmentation. Four groups of patients (CIN 1-3 an d control) with 10 subjects each were examined. In total, the fractal dimen sions of 1200 nuclei were calculated. Results. We found that the fractal dimensions of the nuclei increased as th e degree of dysplasia increased. There were significant differences between control and atypical nuclei found by an analysis of variance. Atypical nuc lei associated with CIN 1, CIN 2, and CIN 3 also differed significantly amo ng these groups. Conclusion. We conclude that the fractal dimension is a valuable tool for d etecting irregularities in atypical nuclei of the cervix uteri and thus all ows objective nuclear grading. (C) 1999 Academic Press.