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The development of automated systems for metaphase location in cytogenetic preparations of human bone marrow

University of British Columbia

Cytogenetic evaluation of human bone marrow cells is one of the principal sources of diagnostic and prognostic information in the evaluation of the myeloid leukemias. In the majority of cases, these diseases are characterized by non-random chromosomal changes in the cells of the malignant clone. The chromosomal abnormalities are present only in the leukemic cells, which are distributed along with normal cells in the bone marrow and throughout the circulation. The objective of this thesis was to test the hypothesis that suitable criteria could be established for automated metaphase detection using human bone marrow preparations. This involved computerized, low resolution scanning of a specimen slide, and the measurement of object features which allowed metaphases to be adequately distinguished from nuclei and debris. Two approaches were investigated. The first used a line-scanning system, in which microscope slides were scanned line by line with a linear CCD detector, and focussing was performed automatically. Eighteen signal features were measured for each detected object. Three group discriminant function analysis was performed on objects from a large number of slides from both types of preparations, in order to distinguish metaphases from nuclei and debris. The second method evaluated the use of a frame scanning system. Objects were detected in a frame-by-frame scan of microscope slides, using a two dimensional CD camera. Feature measurements were performed for all objects within a specified area range, and three group discriminant function analysis was performed on data from a large number of slides. In both approaches, the performance of the discriminant functions was evaluated on independent samples collected from a number of patients, in order to determine the operational error rates of the systems. The sensitivity of the line scan system for metaphase detection was 86%, compared to 92% fror the frame scannning system, while the specificity was 84% for the line scan system, and 86% for the frame scanning system. The frame scan system was shown to be useful for determining the mitotic index of cells cultured for varying periods of time prior to fixation. Four patients with AML were examined, and the results of the analysis show that the mitotic indices could be determined in this way to an accuracy of approximately 5%. The mitotic indices differed as a function of time for different patients.

Text

2011-02-10

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http://hdl.handle.net/2429/31155

Physics

University of British Columbia

Graduate