Image analysis of atypical bronchial squamous epithelial cells. A quantitative and qualitative examination of squamous cell carcinogenesis.

Atypical bronchial squamous epithelial cells from cigarette smokers were digitized using a high-resolution microphotometric scanning system operating at a wavelength of 530 nm. All cells used for the purpose of developing a training set as well as those used as a test set were classified by a team of three cytopathologists. Reduction in the dimensionality of the feature space and cell classification were performed using a new system known as the atypia status index (ASI); this dual-purpose system will specifically classify cells into five distinct classes of progressive atypia as well as quantitate the degree of atypicality of each individual cell. The distribution of cellular ASI values was arranged from lowest to highest and plotted for each subject as a profile. The ASI range has well-defined intervals, representing the five different atypia classes used in the study (squamous metaplasia, mild atypia, moderate atypia, severe atypia and carcinoma). Subjects at different stages of carcinogenesis were found to have significantly different profiles (P less than 0.01). Changes in visual morphologic characteristics and their relation to changes in ASI values for the five different classes of atypia are presented.