Observer variability in microcomputer-assisted morphometric study of nuclear parameters.
To evaluate observer variability during microcomputer-assisted planimetry, nuclear features (area, perimeter, and form factor) were studied in a case of malignant lymphoma. Tissue fixed in glutaraldehyde, embedded in plastic and sectioned at 1 micron was studied using a Zeiss Kontron IBAS 2000 image analysis system. Manual tracing of nuclear outline was performed to obtain the parameters. Both interindividual and intraindividual reproducibilities were evaluated, the former among 8 observers and the latter by the observers repeating the measurements. With the present technique, intraindividual reproducibility was high and correlation was excellent for area, perimeter and form factor measurements. A high degree of interindividual inconsistency was demonstrated for all parameters. Interindividual correlation was poor for form factor. It is concluded that poor interindividual reproducibility even when the objective method of morphometry is used may be a significant problem in tissue investigations, especially when results from different laboratories are being compared.