Development of a Poikilocyte Measuring Method Using Image Analysis Software

ABSTRACT

BACKGROUND: To achieve consistency in poikilocytes grading in peripheral blood cell examinations, we made an image-based differential count (IDC) software to measure the degree of abnormalities in individual red blood cells (RBCs) and relative fractions of poikilocytes. METHODS: Thirty peripheral blood samples were analyzed. Smear slides were examined on a microscope with charge-coupled device (CCD) camera. To verify this program, we compared the IDC results with the results of manual differential counting (MDC). Relative fractions of schistocytes, echinocytes, and elliptocytes were measured by IDC and MDC. The error rate of IDC was measured by confirming the final processed images of IDC. Correlations of IDC and MDC results were compared using linear regression analysis and the time required for each test was measured. For presentation of the mathematical decision criteria of poikilocytes, IDC algorithms for recognizing schistocytes, echinocytes, and elliptocytes were made using simple geometrical or mathematical formulas. RESULTS: The error rate of IDC was 2.8%. For analysis of 1,000 RBCs, MDC took 7.3 minutes and IDC took 2.7 minutes. Linear regression coefficients were 0.776 (P<0.001) for schistocytes, 0.895 (P<0.001) for echinocytes, and 1.001 (P<0.001) for elliptocytes. CONCLUSIONS: It was possible to define poikilocytes with geometrical or mathematical formulas using image analysis programs. The IDC program would be helpful for consistent grading of poikilocytes.