Informatics, digital & computational pathology
Digital and whole slide imaging
WSI applications
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PubMed Search: Whole slide imaging applications
Table of Contents
Definition / general | Essential features | Key components | Terminology | Diagrams / tables | WSI for clinical diagnosis | WSI for education | WSI for quality assurance | Research and image analysis algorithms | Videos | Additional references | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2Cite this page: Rojansky R, Parwani A. WSI applications. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/informaticswholeslideapp.html. Accessed April 23rd, 2024.
Definition / general
- Whole slide imaging involves the acquisition of digital images from glass slides using slide scanners
- Whole slide images (WSI) are fundamentally different from glass slides in that they can be:
- Viewed remotely through online software
- Accessed simultaneously by several viewers
- Annotated digitally
- Processed computationally
Essential features
- WSI can be used for:
- Clinical diagnosis
- Education
- Quality assurance
- Research and image analysis
Key components
- Applications of whole slide imaging typically require:
- Whole slide scanner and scanning staff
- Image viewer software platform
- High resolution screen and pointer device (mouse, joystick, trackpad or other tailored pointer)
Terminology
- Digital pathology: refers to pathologic diagnosis made entirely from WSI without recourse to glass slides
- Telepathology: refers to digital pathology performed at a distance from the originating site of the slides / specimen
- Computer aided diagnosis: refers to a technology or system used for interpreting findings on medical images; may refer to pathology, radiology or other medical images
Diagrams / tables
Contributed by Rebecca Rojansky, M.D., Ph.D.
WSI annotation
WSI for clinical diagnosis
- Primary diagnosis:
- Platforms:
- Philips IntelliSite Pathology Solution (PIPS) became the first FDA granted WSI system, including scanner and image management system (IMS) in April 2017
- Leica Aperio AT2 DX WSI system, including scanner and Image Scope viewing software, was FDA cleared in June 2019 and the Sectra digital pathology module was cleared in April 2020 for use with the Aperio scanner
- Paige.AI Full Focus IMS became FDA cleared in July 2020
- Numerous platforms are approved for clinical use outside of the United States, including the Roche Ventana DP 200 slide scanner with uPath IMS, Zeiss Axioscan Z1, 3DHistech Pannoramic scanners and Pannoramic viewer, Hamamatsu NanoZoomer scanners, NDP.serve3 IMS and NDP.view2 viewer
- Algorithms:
- Several automated image analysis algorithms have been FDA approved and CE marked, including Bioview HER2 FISH, Paige Prostate, lung ALK quantitation and hematology FISH assays (J Pathol Inform 2019;10:2)
- Additional algorithms have been CE marked in the European Union, including 3DHistech MembraneQuant and NuclearQuant, Visiopharm VDS Ki67 module for breast and Paige Breast for breast cancer prediction (J Pathol Inform 2019;10:2)
- Advantages:
- Users can annotate WSI as they would glass slides, including flagging areas of interest, measuring features and writing notes
- WSI software platforms allow for creation of work lists and personalized image archives
- WSI can be shared with other users in real time and without geographic restrictions
- Archiving of WSI enables rapid retrieval of prior patient material to decrease turnaround time (TAT)
- Primary diagnosis and consensus conferences within departments or practices can be conducted remotely (see Remote reporting section below)
- Platforms:
- Remote reporting:
- Remote reporting from WSI can be achieved with appropriate hardware, software, internet connectivity and validation (J Pathol Inform 2021;12:20, J Pathol Inform 2021;12:3)
- Center for Medicaid Services waived the requirement for pathologists to perform diagnostic tests in Clinical Laboratory Improvement Amendments (CLIA) licensed facilities during the coronavirus disease 2019 (COVID-19) pandemic, to support the health and safety of medical staff (Mod Pathol 2020;33:2115)
- Intraoperative consultations:
- Remote intraoperative consultation allows on call pathologists to digitally review frozen sections (Am J Clin Pathol 2020;153:198)
- Use cases:
- Small volume hospitals that may not have a full time pathologist available
- Helpful in countries where there are pathologist shortages (Pathology 2005;37:5)
- Facilitates coverage of multiple sites, coordinated from a single centralized site (Semin Diagn Pathol 2009;26:165, Arch Pathol Lab Med 2018;142:369)
- Can be used for quality assurance (J Pathol Inform 2012;3:45)
- Advantages:
- Faster alternative to remote control robotic microscopes (more akin to usual slide review)
- Facilitates expansion to multiple sites
- After hours call can be covered remotely and be supported by subspecialist pathologists (J Pathol Inform 2014;5:15, J Digit Imaging 2013;26:668)
- Can access historical patient cases in real time
- Helps achieve recommended time to diagnosis for intraoperative consultations (typically around 20 minutes)
- Rapid on site evaluations in cytology:
- Facilitates remote assessment of adequacy for cytology biopsies for rapid on site evaluations (J Pathol Inform 2015;6:19)
- Typically requires a platform capable of acquiring data from sequential focal planes
- Multidisciplinary case conferences (also known as tumor boards or multidisciplinary team meetings):
- Forum for pathologist participation in discussions and management recommendations
- WSI allows pathology data to be accessed and viewed in real time (Diagnostic Histopathology 2014;20:470, J Pathol Inform 2014;5:41)
- Second opinion consultations and outside pathology review:
- Consultations (for expert opinion) often requires sending original materials to the consult institution; in this case, consult services may retain original materials
- WSI can be transferred without loss of original material or risk of different material present on recuts (CMAJ 2013;185:135, Diagnostic Histopathology 2014;20:470)
- Dedicated web based whole slide image platforms are available to facilitate consultation (Arch Pathol Lab Med 2015;139:627)
- Interinstitutional telepathology:
- Decreased turnaround time verses shipping glass slides
- Removes the selection bias of static telepathology
- Improves collaboration between the consult requestor and the consultant (through use of annotation features within WSI viewing software)
- Provides opportunities for quality assurance, archiving and education
- Challenges:
- Cost of transitioning to WSI (J Pathol Inform 2014;5:33)
- Change of workflow in the laboratory to optimize slides for scanning (J Pathol Inform 2014;5:43)
- IT infrastructure required to maintain high speed communication at all times
- Guidelines for validation of WSI for clinical applications are available from:
- Digital Pathology Association (DPA), 2011 (Digital Pathology Association: Validation of Digital Pathology in a Healthcare Environment [Accessed 25 March 2022])
- College of American Pathologists (CAP), 2013 (Arch Pathol Lab Med 2013;137:1710)
- Royal College of Pathologists, 2013 (Royal College of Pathologists: Telepathology - Guidance from The Royal College of Pathologists [Accessed 25 March 2022])
- American Telemedicine Association, 2015 (J Pathol Inform 2015;6:13)
- Spanish Society of Anatomic Pathology, 2015 (Sociedad Española de Anatomía: Libro Blanco de la Anatomía Patológica en España - Recomendaciones de los Clubes para el Diagnóstico Anatomopatológico [Accessed 25 March 2022])
- Korean Society of Pathologists (J Pathol Transl Med 2020;54:437)
WSI for education
- WSI is useful for multidisciplinary case conferences and teaching rounds:
- Reduces preparation time required for conference presentations
- Enables access to past cases, should the need arise during a conference
- Standardized examinations:
- Facilitates multiple examination sites
- Provides improved image quality over snapshot images
- Continuing education:
- Provides access to high quality educational material to learners in disparate locations
- Society conferences:
- Interesting case submissions in WSI format, eliminate the need for multiple recut sections
- Materials can be made available both before and after the conference period
- Online image repositories:
- Several image databases are publicly available for educational and research purposes, including the following:
- References: APMIS 2012;120:305, J Pathol Inform 2022;13:100117
WSI for quality assurance
- Studies have utilized WSI for quality assurance assessment of histology (Lancet Oncol 2019;20:e253, Hum Pathol 2006;37:322)
- WSI may be used to standardize reagent concentrations, over time and within an institution
- Useful for regulatory requirements, such as the required 5 year look back for diagnoses that are worse than a high grade squamous intraepithelial lesion in Pap smears
- Can be used for medicolegal review and secondary review of cases with newly diagnosed malignancies (which is required in some practices)
Research and image analysis algorithms
- WSI enables image analysis of pathology slides for research and computer assisted diagnosis
- Quantitation tasks:
- Automated calculation of breast biomarkers: estrogen receptor, progesterone receptor and HER2 (J Pathol Inform 2013;4:19, Pathol Res Pract 2014;210:713, Mod Pathol 2016;29:318)
- Ki67 counting (Am J Surg Pathol 2012;36:1761)
- Mitosis detection (Med Image Anal 2015;20:237)
- Rare event identification:
- Finding microorganisms (Am J Clin Pathol 2010;133:849)
- Counting glomeruli in renal biopsies (PLoS One 2016;11:e0156441)
- Quantification of fibrosis and fat (Pathol Int 2013;63:305)
- Diagnostic assistance:
- Finding ductal carcinoma in situ in breast tissue (IEEE Trans Med Imaging 2016;35:2141)
- Gleason scoring of prostate cancer (Mod Pathol 2020;33:2058)
- WSI for research applications:
- Central review for clinical trials (Arch Pathol Lab Med 2013;137:492)
- Peer review and working groups (Toxicol Pathol 2015;43:1149)
- Novel tumor classification schemes:
- Prognostication based on epithelium to stroma ratio (Diagn Pathol 2012;7:22)
- Risk stratification based on variations in lymphocyte subtypes of tumor microenvironment (J Transl Med 2012;10:205)
- Increasing area of investigation in the correlation of WSI data with other data streams (clinical, pathologic or genomic)
Videos
Creating whole slide images with a robotic microscope stage
Whole slide images for diagnostic pathology
Additional references
Board review style question #1
Which of the following is true regarding the College of American Pathologists guidelines for the use of whole slide imaging (WSI) for primary diagnosis?
- Each laboratory employing WSI for primary diagnosis should independently validate their WSI implementation
- No validation is recommended so long as laboratories use FDA approved WSI systems
- Pathologists who use WSI for primary diagnosis must have special certification
- WSI must be separately validated for each tissue type and application
Board review style answer #1
A. Each laboratory employing WSI for primary diagnosis should independently validate their WSI implementation
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Reference: WSI applications
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Reference: WSI applications
Board review style question #2
Which of the following activities constitutes use of whole slide images for primary diagnosis?
- Correlating whole slide images of a prior biopsy with slides of a current resection specimen
- Sending whole slide images to a colleague for consultation
- Sharing whole slide images at tumor board to guide medical management
- Signing out a case remotely after reviewing the whole slide images
Board review style answer #2
D. Signing out a case remotely after reviewing the whole slide images
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Reference: WSI applications
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Reference: WSI applications
