A quantitative approach to evaluate image quality of whole slide imaging scanners

Abstract

Context:The quality of images produced by whole slide imaging (WSI) scanners has a direct influence on the readers’ performance and reliability of the clinical diagnosis. Therefore, WSI scanners should produce not only high quality but also consistent quality images.Aim:We aim to evaluate reproducibility of WSI scanners based on the quality of images produced over time and among multiple scanners. The evaluation is independent of content or context of test specimen.Methods:The ultimate judge of image quality is a pathologist, however, subjective evaluations are heavily influenced by the complexity of a case and subtle variations introduced by a scanner can be easily overlooked. Therefore, we employed a quantitative image quality assessment method based on clinically relevant parameters, such as sharpness and brightness, acquired in a survey of pathologists. The acceptable level of quality per parameter was determined in a subjective study. The evaluation of scanner reproducibility was conducted with Philips Ultra-Fast Scanners. A set of 36 HercepTest™ slides were used in three sub-studies addressing variations due to systems and time, producing 8640 test images for evaluation.Results:The results showed that the majority of images in all the sub-studies are within the acceptable quality level; however, some scanners produce higher quality images more often than others. The results are independent of case types, and they match our perception of quality.Conclusion:The quantitative image quality assessment method was successfully applied in the HercepTest™ slides to evaluate WSI scanner reproducibility. The proposed method is generic and applicable to any other types of slide stains and scanners.

[Paper] Automatic Quality Evaluation of Whole Slide Images for the Practical Use of Whole Slide Imaging Scanner

“…In WSI applications, the main issue is focus error and noise 7,[27][28][29] for quality management of digital pathology. presented a method to evaluate the quality of WSI with the intension to measure the scanner reproducibility 27) .…”

Can Whole Slide Imaging Replace Conventional Microscopic Evaluation? A Comparative Study over a Spectrum of Cases

“…It is a known problem that the same slide scanned by same scanner at different times may appear different due to external factors including temperature and mechanical shifts. With the advent of computer-based diagnostics, high quality and reproducibility of scanned images can directly impact the diagnosis [5]. Quality of the image is also affected by factors such as thickness of the section, staining and fixation which are difficult to standardize.…”

4f Koehler Transmitted Illumination Condenser for Teaching and Low-Cost Microscopic Imaging

“…Although postprocessing may improve image quality, it is not enough to compensate for limited quality in the recorded data (6). Nonuniform illumination, saturated regions, fluctuating brightness, and excessive cluttering are examples of factors limiting the quality of acquired images (7,8) and the reproducibility of quantitative analyses made from them (9). The system resulting from this protocol addresses these limitations by ensuring uniform illumination and reduced cluttering from increased NA, which ensures sectioning capability.…”