Performance evaluation and validation of automated digital image analysis in peripheral blood cells morphology examination

Abstract

Objective: To verify and evaluate the performance of automated digital image(DIA) for peripheral blood cell morphology examination. Methods: Three hundred and seventy-nine routine peripheral blood smears and 18 plasmodium positive peripheral blood smears were collected. Blood smears were made and stained by Wright -Giemsa method.White blood cell (WBC) differentiation of blood smears were pre-classified by DIA (DIA direct classification), re-classified (manually reviewed after DIA classification), and artificially classified under microscope. the inter-assay and intra-assay coefficients of variation (CV) of DIA were respectively calculated for repeatability verification. Taking the artificial microscopy as the gold standard, the sensitivity、specificity and accuracy of DIA were calculated. The DIA ability of peripheral blood blast cell morphological count, platelet (PLT) morphological count and morphological examination of plasmodium were also verified. Results: Except for eosinophils and basophils, the inter-assay and intra-assay CV of WBC classification by DIA in normal samples were < 10%. The CV of WBC classification in abnormal samples increased with the decrease of cell percentage. The sensitivity, specificity and accuracy of DIA pre-classification were 90.5%, 99.2%, 98.2%. Through pre-classification and re-classification by DIA,the results of the blood smears which triggered blast cell alarm had a good correlation with manual classification(r=0.812, 0.983, both P<0.01). The PLT morphological count by DIA had high correlation with hematology analyzer (r=0.946, P<0.01). The deviation absolute value of two methods of PLT count was < 15%, while in PLT aggregation or giant thrombocytosis samples,the deviation absolute value of PLT count by two methods was > 15%. After image acquisition by DIA, 17 plasmodium trophozoites were detected in 18 plasmodium-positive peripheral blood smears, and the images were clear. Conclusions: The DIA system has good repeatability, high sensitivity, specificity and accuracy in peripheral blood WBC classification. Its pre-classification and re-classification results have high correlation with the manual classification results.