DNA ploidy analysis and its role in the detection of malignancy

The increasing incidence rate and mortality rate of cancer have stimulated the research for prevention, early diagnosis and appropriate treatment. DNA ploidy status of tumor cells is an important parameter with diagnostic and prognostic significance. In the current study DNA ploidy analysis was performed using digital image processing techniques. A normal human cell contains 46 chromosomes. In nonmalignant tumors (benign) all the cells will be containing this number of chromosomes. In malignant tumors, because of the loss of the nuclear control mechanism, many of the cells will show abnormal number of chromosomes. Normal cells will be containing 23 pairs of chromosomes and is denoted as 2N. When cells are stained with nuclear stains like haematoxyline or DNA stains like feulgen, the size and color depth of the nucleus depends on the number of chromosomes. So by analyzing the stained nucleus we can get an idea of the chromatin content of the cell. This paper implements a method to determine the nuclear DNA content and to distinguish between malignant and nonmalignant tumors. Here global region based active contours are used for cell segmentation. After segmentation the sum of gray value (DNA index) of individual nucleus are calculated and DNA ploidy histograms are plotted for malignant and nonmalignant cases. The variance and mean of gray values calculated for individual nucleus can be used as a factor for distinguishing malignant and nonmalignant cells.