Automatic scoring of sister chromatid exchanges by image analysis in a dose response experiment

A system which automatically selects second division metaphases and then, automatically scores the number of SCEs of each cell is described. In an initial set of experiments, the performance of the components of the system was measured using a data set in which metaphases had been visually classified as either 2nd division or other; and in 2nd division metaphases, every SCE had been marked on a hard copy. SCE scoring had a true positive rate of about 75% and a false positive rate of about 1.5 false SCEs per metaphase analyzed. Second division detection had a true positive rate of 80% and a false positive rate of about 10% of the non-2nd division cells. Next, the overall system was compared to human visual scoring in a dose-response experiment by analyzing the effect of mitomycin C on human chromosomes scored visually by two observers and by the fully automatic scoring. Human visual scoring and machine analysis showed similar dose responses, but the variability between them was considerable.