Impact of Stain Normalization on Pathologist Assessment of Prostate Cancer: A Comparative Study

Abstract

In clinical routine, the quality of whole-slide images plays a key role in the pathologist’s diagnosis, and suboptimal staining may be a limiting factor. The stain normalization process helps to solve this problem through the standardization of color appearance of a source image with respect to a target image with optimal chromatic features. The analysis is focused on the evaluation of the following parameters assessed by two experts on original and normalized slides: (i) perceived color quality, (ii) diagnosis for the patient, (iii) diagnostic confidence and (iv) time required for diagnosis. Results show a statistically significant increase in color quality in the normalized images for both experts (p < 0.0001). Regarding prostate cancer assessment, the average times for diagnosis are significantly lower for normalized images than original ones (first expert: 69.9 s vs. 77.9 s with p < 0.0001; second expert: 37.4 s vs. 52.7 s with p < 0.0001), and at the same time, a statistically significant increase in diagnostic confidence is proven. The improvement of poor-quality images and greater clarity of diagnostically important details in normalized slides demonstrate the potential of stain normalization in the routine practice of prostate cancer assessment.

Advances in radiology and pathology of prostate cancer: a review for the pathologist

“…Not only do whole-slide images allow pathologists to accurately quantify and measure microscopic features, but, for example, even the pre-analytical variability responsible for stain variation can be reduced using normalization techniques. These techniques have been shown to increase the speed and confidence of pathologists when dealing with poorly stained slides 88 .…”