Virtual Microscopy System for Blood Morphology Evaluation and Their Applications in Hematology

We have explored the possibilities of a new technology for scanning peripheral blood slides converting the images to a digital slide that can be observed in a manner similar to a microscope.

Objectives: To evaluate the quality of peripheral blood (PB), bone marrow (BM) and body fluids (BF) images obtained in a Digital Slide Scanner in different hematological or non hematological diseases and to analyse the useful of this System in Hematology.

Material and Methods: We obtained PB samples from 13 patients with the following diagnoses: 3 acute myeloid leukemia (AML), 1 acute lymphoid leukemia (ALL), 2 B-cell neoplasm, 2 myeloproliferative disease (MPD): 1 chronic myeloid leukemia (CML) and 1 myelofibrosis, 3 Plasmodium infections (2 falciparum and 1 vivax), 1 sickle cell anemia and 1 congenital sideroblastic anemia (CSA). We also analysed 2 BM (leishmania and parvovirus infections) and 1 BF (melanoma) samples. We used a NanoZoomer Digital Pathology or NDP (Hamamatsu System, Japan) for scanning the different glass slides using 40X objective lens. A small fragment of the most appropriate area was selected and the focus was set up at different levels. Each one of the digital slides was saved in digital data and the images were analysed using the NDP software.

Results: Most values of the file sizes were approximately 300 MB for PB and BM and 50 MB for body fluid. All digital slides showed a very high image quality. It was possible to evaluate the blood cell morphology using 20X, 40X, 63X and 100X magnifications. We selected 63X as the best one for the combination size of the cells and precision in the focus. Similar to microscopic observation, myeloid and lymphoid blast cells in digital slides showed different morphologic features (cytoplasmic inclusions, primary granules, prominent vacuolation…) allowing hematological diagnosis. Myeloproliferative disorders showed a high degree of morphological abnormalities in the erythroid, granulocytic and megakaryocytic lineages. B chronic haematological neoplasms were identified in the virtual slides by morphological criteria. With respect to Plasmodium infections, the virtual images allowed examination of morphological features of both the parasites and the host red cells, facilitating the species diagnosis. Sickle cells were easily identified. Pappenheimer bodies were visible in the erythrocytes of the CSA. With respect to BM and BF, digital slides showed the morphological abnormalities for the diagnosis. The software let to calculate the diameter and the area of the blood cells.

Conclusions: Our results showed that the virtual microscopy for blood morphology evaluation can be used to substitute the glass smear samples in Hematology External Quality Assessment. In addition, the application of the NDP software may be useful in morphometric analysis of pathological cells in different hematological diseases.