Objective: To evaluate DNA image cytometry (ICM) in tissue sections, human and rat liver was used as a model. These tissues have distinct DNA ploidy histograms of mainly diploid (human) and predominantly tetraploid (rat) plus octaploid nuclei.
Study design: Section thickness varied from 4 to 12 microns in rat liver and 4 to 10 microns in human liver, in steps of 2 microns. The measurements were made using a commercially available ICM system, strictly following a measurement protocol.
Results: Four-micrometer-thick sections gave very broad histograms. Six-micrometer-thick sections gave better results, but with increasing DNA PLOIDY (> 4c), modal peaks were broad and increasingly shifted to the left. Sections of 8-10 microns gave linear results of the 2c, 4c and 8c peaks and also the narrowest peaks. The 12-micron sections of rat liver were more difficult to measure, and the results were not improved.
Conclusion: The 8-micron sections gave the best results and were easiest to measure. These results are promising, but since liver is a fairly simple model, further studies are required to elucidate whether DNA ploidy measurements can be performed reliably on tissue sections of human tumors.