Twenty Years of Digital Pathology: An Overview of the Road Travelled, What is on the Horizon, and the Emergence of Vendor-Neutral Archives

Abstract

Almost 20 years have passed since the commercial introduction of whole-slide imaging (WSI) scanners. During this time, the creation of various WSI devices with the ability to digitize an entire glass slide has transformed the field of pathology. Parallel advances in computational technology and storage have permitted rapid processing of large-scale WSI datasets. This article provides an overview of important past and present efforts related to WSI. An account of how the virtual microscope evolved from the need to visualize and manage satellite data for earth science applications is provided. The article also discusses important milestones beginning from the first WSI scanner designed by Bacus to the Food and Drug Administration approval of the first digital pathology system for primary diagnosis in surgical pathology. As pathology laboratories commit to going fully digitalize, the need has emerged to include WSIs into an enterprise-level vendor-neutral archive (VNA). The different types of VNAs available are reviewed as well as how best to implement them and how pathology can benefit from participating in this effort. Differences between traditional image algorithms that extract pixel-, object-, and semantic-level features versus deep learning methods are highlighted. The need for large-scale data management, analysis, and visualization in computational pathology is also addressed.

Keywords: Computational pathology; digital pathology; image analysis; informatics; vendor neutral archive; whole-slide image.

Figure 1

Screenshot of the early Johns Hopkins/University of Maryland “Virtual Microscope” whole-slide imaging viewer client

Figure 2

Architecture of the active data repository spatial data query system used as the virtual microscope backend

Figure 3

Architecture of the DataCutter system used to support the Virtual Microscope application

Figure 4

Overview of a whole-slide imaging system comprised of integrated scanner and workstation components (Image reproduced with permission)

Figure 5

Various hybrid whole slide imaging/live robotic instruments showing the number and magnification of objectives for each device

Figure 6

An example of how a vendor-neutral archive might be integrated in a health system

Figure 7

An outline of FeatureDB for managing pathomic features and helping fuse clinical data and pathomic feature data for various analytical and visual data exploration and processing systems

Figure 8

Scientific mashups and visual analytics for interactive exploration of fused rad/path/clinical data. Such visual explorations help researchers examine the scope and extent of data, create specific cohorts, and formulate hypotheses