Automated enumeration of cellular composition in bone marrow aspirate with the CELL-DYN 4000 automated hematology analyzer

Digital assessment of peripheral blood and bone marrow aspirate smears

The diagnosis of benign and neoplastic hematologic disorders relies on analysis of peripheral blood and bone marrow aspirate smears. As demonstrated by the widespread laboratory adoption of hematology analyzers for automated assessment of peripheral blood, digital analysis of these samples provides many significant benefits compared to relying solely on manual review. Nonetheless, analogous instruments for digital bone marrow aspirate smear assessment have yet to be clinically implemented. In this review, we first provide a historical overview detailing the implementation of hematology analyzers for digital peripheral blood assessment in the clinical laboratory, including the improvements in accuracy, scope, and throughput of current instruments over prior generations. We also describe recent research in digital peripheral blood assessment, particularly in the development of advanced machine learning models that may soon be incorporated into commercial instruments. Next, we provide an overview of recent research in digital assessment of bone marrow aspirate smears and how these approaches could soon lead to development and clinical adoption of instrumentation for automated bone marrow aspirate smear analysis. Finally, we describe the relative advantages and provide our vision for the future of digital assessment of peripheral blood and bone marrow aspirate smears, including what improvements we can soon expect in the hematology laboratory.

Analysis of bone marrow aspiration fluid using automated blood cell counters

Cytomorphological examination of aspirate smears remains the basic method to diagnose hematologic disorders and to evaluate treatment-related changes. Last-generation hematological analyzers can count, besides cells normally circulating in peripheral blood, some types of immature and abnormal cells, such as erythroblasts and immature granulocytes. The complex nature of bone marrow fluid, however, has prevented until now the routine utilization of blood cell counters in this area. Recent studies have shown the possibility of using bone marrow fluid as a substitute for peripheral blood for clinical tests in particular situations and for repetitive cytologic examinations in specific clinical and research fields.

Automation of bone marrow aspirate examination using the XE-2100 automated hematology analyzer

BACKGROUND

Attempts to analyze bone marrow aspirates have been reported with the use of several automated blood cell counters, but sufficient accuracy in examination is not acquired yet. Major problems have included difficulties in correctly differentiating various immature cells and interference by lipid in bone marrow aspirates. The goal of this study was to solve these problems to attain more accurate assessment of bone marrow aspirates with automated blood cell counters.

METHODS

We modified the XE-2100 Automated Hematology Analyzer (Sysmex Corporation, Kobe, Japan) to fit it for bone marrow aspirate measurement and evaluated its performance. Measurements were performed with the modified XE-2100 on 81 patient samples of bone marrow aspirates; as a reference, the manual visual method was used and flow cytometric analysis were carried out.

RESULTS

Good correlations between results with the modified XE-2100 and the manual visual method were obtained for total nucleated cell count (TNCC; r = 0.99), erythroblast/TNCC ratio (r = 0.93), and myeloid cell/TNCC ratio (r = 0.75).

CONCLUSIONS

When this device is used, bone marrow aspirate differentials can be determined quickly and easily. This device will be useful for preliminary examination to obtain a summary of various blood cell ratios in bone marrow aspirates before performance of microscopic examination.

Automatic analysis of normal bone marrow blood cells using the XE-2100 automated hematology analyzer

The bone marrow aspiration test conventionally has been performed by visual methods, using a light microscope, because automatic blood cell analyzers cannot adequately capture erythroblasts and immature granulocytes (IGs) (Tatsumi et al.: Osaka City Med J 1988;34:135-146; Tatsumi et al.: Am J Clin Pathol 1986;86:50-54). With the development of the XE-2100 automatic blood cell analyzer (Sysmex Corporation, Kobe, Japan) in 1999, the classification of erythroblasts and IGs by means of flow cytometry (Zini et al.: Infus Ther Transfus Med 2001;28:277-279; Briggs et al.: Sysmex J Int 1999;9:113-119) became possible. In the present study we classified cells in 65 bone marrow aspiration specimens by the microscopic method and with the XE2100, and compared the results. A good correlation was found in the nucleated red blood cell (NRBC), white blood cell (WBC), and total nucleated cell (TNC) counts; the myeloid/erythroid ratio (M/E ratio); neutrophils, lymphocytes, eosinophils, and IGs in the immature myeloid information (IMI) channel; and the total cell count. These items can all be analyzed in about 54 sec with the XE2100, which is faster than with the microscopic method. Therefore, analysis of bone marrow aspiration specimens with this apparatus appears to be very useful for clinical screening as well as laboratory testing.

Possible automatic cell classification of bone marrow aspirate using the CELL-DYN 4000 automatic blood cell analyzer

In clinical hematology, the demand for bone marrow aspiration testing is increasing. However, conventional automatic blood cell analyzers cannot completely analyze erythroblasts, and evaluation has mainly been performed by visual examination (the microscopic method). Using the CELL-DYN 4000 automatic blood cell analyzer (CD4000) (Abbott Laboratories, North Chicago, IL), specific recognition and classification of erythroblasts by DNA staining is possible. In the present study, using bone marrow blood collected from normal subjects and patients with hematological malignancy, we classified cells by the microscopic method and with the CD4000, and compared the results. Good correlations were found for total nucleated cell count (TNCC), neutrophils, lymphocytes, erythroblasts, and the myeloid series to erythroid series (M/E) ratio. It is possible to detect blasts that emerge in patients with hematological malignancy using the blast flag system installed on the CD4000. Since all of the items can be analyzed in about 80 sec with the CD4000, cells in bone marrow aspirates can be classified faster with this apparatus than by the microscopic method. Therefore, analysis of bone marrow aspirates with this apparatus appears to be very useful not only for laboratory testing but also for clinical screening.

Automated image processing. Past, present, and future of blood cell morphology identification

Automated image processing analysis for leukocyte differential counting started 30 years ago principally as a mimic of the traditional microscopic method. Several types of systems were used in the 1970s and 1980s. In the late 1990s, two new image processing systems were developed with new technology for cell image analysis. They possess an intelligent neural network software and can be connected to an Ethernet for telehematologic diagnosis and consultation.