Potential quality pitfalls of digitalized whole slide image of breast pathology in routine practice

Nehal M Atallah,Michael S Toss,Clare Verrill,Manuel Salto-Tellez,David Snead,Emad A Rakha

doi:10.1038/s41379-021-01000-8

Abstract

AbstractUsing digitalized whole slide images (WSI) in routine histopathology practice is a revolutionary technology. This study aims to assess the clinical impacts of WSI quality and representation of the corresponding glass slides. 40,160 breast WSIs were examined and compared with their corresponding glass slides. The presence, frequency, location, tissue type, and the clinical impacts of missing tissue were assessed. Scanning time, type of the specimens, time to WSIs implementation, and quality control (QC) measures were also considered. The frequency of missing tissue ranged from 2% to 19%. The area size of the missed tissue ranged from 1–70%. In most cases (>75%), the missing tissue area size was <10% and peripherally located. In all cases the missed tissue was fat with or without small entrapped normal breast parenchyma. No missing tissue was identified in WSIs of the core biopsy specimens. QC measures improved images quality and reduced WSI failure rates by seven-fold. A negative linear correlation between the frequency of missing tissue and both the scanning time and the image file size was observed (p < 0.05). None of the WSI with missing tissues resulted in a change in the final diagnosis. Missing tissue on breast WSI is observed but with variable frequency and little diagnostic consequence. Balancing between WSI quality and scanning time/image file size should be considered and pathology laboratories should undertake their own assessments of risk and provide the relevant mitigations with the appropriate level of caution.

Highlights

The introduction of digitalized whole slide image (WSI) technology has attracted a great deal of attention in the pathologists’ community where the use of digital pathology (DP) for primary diagnosis is becoming commonplace[1,2,3,4]
Producing optimal quality WSIs depends on the skills of a well‐trained operator who guides the scanning procedure in addition to robust quality control (QC) measures starting from receiving the specimen through fixation, processing, and slide preparation prior to the actual scanning process and acquisition of the WSIs7
To facilitate slide scanning at a large scale in routine histopathology reporting, it is desirable for scanner manufacturers to provide fast high throughput scanners able to deal with the volume of slides produced by modern laboratories, whilst maintaining the image quality

Summary

Introduction

The introduction of digitalized whole slide image (WSI) technology has attracted a great deal of attention in the pathologists’ community where the use of digital pathology (DP) for primary diagnosis is becoming commonplace[1,2,3,4]. The representation of the tissue within the WSI compared to the corresponding glass slides is of crucial importance for the adoption of DP in routine practice for making an accurate diagnosis and sharing challenging cases for a second opinion. Archiving both glass slides and WSIs in routine practice is not cost effective and will require extra resources, it is unlikely that pathology laboratories will abandon storing glass slides and rely on the archived the digitized WSI unless there is evidence-based reassurance that WSI is fully representative of the corresponding glass slides. A largely automated scanning process is required to deliver this, and it important such automation avoids scanning errors from missing low-density tissue such as adipose tissue

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Conclusion