A technique for multiple-cell chromosome karyotyping

Automated multiple-cell karyotyping: a clinical feasibility study

In order to increase the efficiency of the Magiscan metaphase location and karyotyping system, its software and mode of operation have been changed. In the new multiple-cell karyotyping method, interactions by the operator are only required for relocation and counting of metaphases, but not for karyotyping. Metaphases are located and their coordinates recorded automatically as before. The first metaphase in the list is relocated, displayed on the screen, and counted by the operator. It is then karyotyped automatically while the operator relocates and counts the next metaphase in the list. This procedure continues until an appropriate number of metaphases have been counted and karyotyped. Finally a composite karyotype is printed out. Each karyotype is represented by a column of 23 chromosome pairs (1-22 and XX or XY) and all columns are lined up next to each other. Most chromosomes are correctly classified into the composite karyotype. Minor structural abnormalities are detected by comparing pairs of homologues. Overlapped, close touching, and grossly abnormal chromosomes are often misclassified or rejected and shown beneath the classified chromosomes. A trained cytotechnician can easily detect even small chromosome abnormalities on the composite karyotype. A clinical feasibility study indicates that the procedure can be used for routine cytogenetic analysis.

Experience with the Athena semi-automated karyotyping system

The traditional analysis and assembly of metaphase chromosomes into a karyogram is a slow and tedious process requiring intermediate photographic steps and manual manipulation of the chromosome images. Much of this task is highly repetitive and readily lends itself to partial automation. Semi-automated karyotyping systems now are being used increasingly in both clinical and research cytogenetic laboratories. Digital image processing techniques are used to capture, manipulate, and make an initial classification of chromosome images. The Athena system uses commercially available components based on a Macintosh II personal computer. Digital image processing procedures automatically isolate chromosome images from the metaphase and arrange them into a karyogram, using information about relative chromosome length, centromeric index, and banding pattern. The operator uses the intuitive graphics interface of the Macintosh computer to monitor each phase of the analysis, to resolve any problems in isolating chromosome images, and to rearrange the individual chromosome images while assembling the final karyogram. Athena is designed as a semi-automated karyotyping system that is easy to learn and has sufficient power and versatility for routine use in the analysis of human metaphase chromosomes.

The Athena semi-automated karyotyping system

In this article we describe Athena, a system that provides for semi-automated karyotyping of metaphase spreads. The system is based upon the Macintosh II computer. It uses software that is written entirely in C and consists of approximately 200 Kbytes of executable code. Athena provides automated segmentation of metaphase images into individual chromosomes, automated measurements on each banded chromosome, and automated classification into the standard Paris-convention karyotype. Furthermore, the system provides the ability to construct one or more chromosome data bases to represent the types of metaphase spreads and staining techniques that may be used in a given laboratory. Because we believe that it is impossible to construct a system that can achieve perfect segmentation, perfect separation of touching and overlapping chromosomes, perfect localization of the centromeres, and perfect classification, the system offers the possibility for interaction at each of the above stages using the well-accepted Macintosh user interface.