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Randomized Controlled Trial
. 2011 Feb;135(2):233-42.
doi: 10.5858/135.2.233.

Observer variability in the interpretation of HER2/neu immunohistochemical expression with unaided and computer-aided digital microscopy

Marios A Gavrielides  1 , Brandon D Gallas, Petra Lenz, Aldo Badano, Stephen M Hewitt
Affiliations
Randomized Controlled Trial

Observer variability in the interpretation of HER2/neu immunohistochemical expression with unaided and computer-aided digital microscopy

Marios A Gavrielides et al. Arch Pathol Lab Med. 2011 Feb.

Abstract

Context: Observer variability in digital microscopy and the effect of computer-aided digital microscopy are underexamined areas in need of further research, considering the increasing use and future role of digital imaging in pathology. A reduction in observer variability using computer aids could enhance the statistical power of studies designed to determine the utility of new biomarkers and accelerate their incorporation in clinical practice.

Objectives: To quantify interobserver and intraobserver variability in immunohistochemical analysis of HER2/neu with digital microscopy and computer-aided digital microscopy, and to test the hypothesis that observer agreement in the quantitative assessment of HER2/neu immunohistochemical expression is increased with the use of computer-aided microscopy.

Design: A set of 335 digital microscopy images extracted from 64 breast cancer tissue slides stained with a HER2 antibody, were read by 14 observers in 2 reading modes: the unaided mode and the computer-aided mode. In the unaided mode, HER2 images were displayed on a calibrated color monitor with no other information, whereas in the computer-aided mode, observers were shown a HER2 image along with a corresponding feature plot showing computer-extracted values of membrane staining intensity and membrane completeness for the particular image under examination and, at the same time, mean feature values of the different HER2 categories. In both modes, observers were asked to provide a continuous score of HER2 expression.

Results: Agreement analysis performed on the output of the study showed significant improvement in both interobserver and intraobserver agreement when the computer-aided reading mode was used to evaluate preselected image fields.

Conclusion: The role of computer-aided digital microscopy in reducing observer variability in immunohistochemistry is promising.

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Figures

Figure 1.
Figure 1.
Examples of digital immunohistochemical images of HER2-stained, breast cancer tissue samples used in the study. The images were acquired from a 1+ slide (A), a 2+ slide (B), and a 3+ slide (C). Image size for this illustration was reduced from actual size (original magnification ×20).
Figure 2.
Figure 2.
Feature plot shown concurrently with HER2 images in the computer-aided mode of the observer study. The plot shows membrane completeness and membrane staining intensity values of a testing image (star prompt) relative to the values of slides in 1+, 2+, and 3+ categories. Abbreviation: ROI, region of interest, refers to the image shown.
Figure 3.
Figure 3.
A screenshot of the graphic user interface used in the study showing an image being read in the unaided reading mode. Abbreviation: ROI, region of interest, refers to the image shown (HER2 stain, original magnification ×20).
Figure 4.
Figure 4.
A screenshot of the graphic user interface used in the study showing an image being read in the aided reading mode. Abbreviation: ROI, region of interest, refers to the image shown (HER2 stain, original magnification ×20).
Figure 5.
Figure 5.
Mean observer scores in the range of 1 to 100 for the unaided and computer-aided reading modes. Error bars show 1 standard deviation.
See this image and copyright information in PMC

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