Informatics, digital & computational pathology


Telepathology fundamentals

Editor-in-Chief: Debra L. Zynger, M.D.
Ngoc Tran, M.D., M.S.
Lewis A. Hassell, M.D.

Topic Completed: 27 August 2020

Minor changes: 12 August 2021

Copyright: 2018-2021,, Inc.

PubMed Search: Telepathology and implementation[title]

Ngoc Tran, M.D., M.S.
Lewis A. Hassell, M.D.
Page views in 2020: 511
Page views in 2021 to date: 331
Cite this page: Tran N, Hassell LA. Telepathology fundamentals. website. Accessed September 21st, 2021.
Definition / general
Essential features
  • Data capture device (slide scanner, microscope with mounted camera, other primary instrumentation such as flow cytometer, etc.)
  • Suitable connectivity medium with appropriate security and bandwidth for type of data
  • Receiving and review device (mobile device, computer / monitor, other)
  • Data management software, reporting software, interpretive aids and algorithms or image analysis tools and other tools are often desirable but optional
Technology employed
  • Slide scanner (linear scanning or tile by tile followed by image stitching, plus focusing software)
  • Image analysis software (artificial intelligence tools, etc.)
  • Viewing software and hardware (simple and intuitive viewing and manipulation of images is critical to adoption and efficiency)
  • Virtual case management tools (archiving, image extraction, sharing)
  • Reporting (lab information system, electronic health record or paper fax)
Problems addressed
  • Remote consultation
  • Contract central laboratory
    • Technical services can be centralized or offshored (for either clinical or research work) with dissemination of professional or interpretive / manipulative effort via telepathology, most often using whole slide imaging (WSI)
  • Special studies
    • Expands access to specialized processes such as IHC, FISH, CISH, etc., otherwise unavailable in a given location
  • Primary diagnosis - in line scanning
    • All or selected cases scanned and integrated into the histology laboratory workflow with the use of WSI for primary diagnosis
    • Works best with surgical pathology, while cytopathology is more challenging (Cytopathology 2011;22:73)
  • Tumor board - clinical reviews
    • Whole slide images or remote streaming microscopy facilitate remote or on site tumor board presentation and clinician (or patient) slide review, enhancing the ability to adequately present whole slides or whole cases that could be relevant during these conferences
  • Slide archival review
    • Archived digital image materials of an existing patient available for review when presented with a new specimen from this patient or for clinical reassessment
  • Quality assurance
    • Technical processes (staining, control reactivity, proficiency testing)
    • Professional peer review and quality assurance (e.g. random or directed second reviews / over reads) or consensus development on criteria / nomenclature
  • Patient consultation
    • Sharing pathology images with the patient or with the clinical team
    • In granting patient access to their digital image materials, adherence to privacy and security guidelines is required
Goals in implementation
  • Confidential, secure, facile access
  • Extend service to remote populations
  • Expand access to subspecialists or obtain peer consultations
  • Enhance business efficiencies (reduce transport costs, equalize workload)
  • Centralize specialty procedures (e.g. IHC or flow cytometry) while allowing facile distribution of professional revenue from interpretation
Obstacles in implementation
  • Lack of robust instrumentation on both ends (high up time:down time quotient)
  • Lack of available IT personnel and infrastructure
  • Equipment and other capital costs
  • Political opposition or regulatory hurdles
  • Validation, quality control, training issues
  • Compatibility of file types, viewers, data sharing methods
Data transmission, storage, security issues
  • Data transmission rates determined by bandwidth of infrastructure and concurrent usage
  • Large file size and slower transmission rates result in pixilation, delays in loading and slower processes, leading to frustrations on the part of the observer
  • Video streaming requires at least 3 - 5 megabits / sec (Mbps) for download and 2 Mbps for upload speeds
  • File sizes dictate need for abundant storage and well conceived retention / purge plan
  • Data security governed by local governments and regulation may dictate where storage facility must reside
  • Under U.S. law, HIPAA requirements dictate the need for appropriate business agreements for any data traceable to individual patients that is stored outside an institution, such as in the cloud
System components included in the FDA approved devices for primary diagnosis
  • Scanner, image acquisition means
  • Image management system
  • Viewing system (hardware)
System components not included in the FDA approved devices but potentially pertinent to the process
  • Storage system (PACS or server configuration)
  • Interface to other systems, electronic health record (EHR), laboratory information systems (LIS), business systems
  • Case management / reporting / retrieval system
  • Scanners range from single slide scanners to high throughput scanners for large volume operations
  • Scanners may incorporate features of a microscope, including those using ultraviolet (UV) or multispectral wavelength light or be configured to piggyback onto existing microscopes and stitch tiled images together with acquisition
  • Other telepathology image acquisition devices include still or video imaging cameras (including smart phones) for streaming or fixed image capture
  • File storage devices include conventional servers, optical disc media or other solid state or disc drive devices with high enough capacity to store large file sizes
  • Image management includes specification of file type and associated metadata, compression algorithms and file reconstruction methods
  • Image management may also include logic for arrangement of images and associated metadata, like case number or patient demographics, to safeguard patients
  • Viewing system includes the software for image and color representation and appropriate (validated) hardware suited to the application
Selection of system or components and implementation
  • Define needs and purposes to be accomplished
    • Streaming or fixed images to be used
    • Scanning of slides at what magnification
    • Assess workforce issues, plan staffing adjustments / additions and obtain training if needed (NSH certificate in scanning, for example)
    • Evaluate need for additional or upgraded hardware (e.g. monitors) and network demands
    • Engage support from all key stakeholders and identify a leadership group for implementation
    • Select a vendor or vendors (do due diligence!) and interview users
  • Single vendor option
    • FDA approved system is required
    • Limited service options available or constrained market
    • Favorable pricing is available
  • Best of breed option
    • Niche or specialized functionality is needed
    • Validation costs not excessive
    • Service agreements suitable and other costs favorable
  • Implementation via a staged process is preferred to eliminate barriers and solve problems before full scale roll out
  • Ensure that funding model is based on sound assumptions and sustainable over time
Upgrade process and lifespan issues
  • Most scanner and viewer hardware will have a defined lifespan dependent on uses, technological evolution and availability of technical support
  • Scientific and technical advances in data and image management impinge on lifespan
  • Political and social environment also impact use cases, e.g. pandemic experience
Regulatory concerns and validation
  • Whole slide imaging systems for primary diagnosis: class II FDA device
  • Streaming video for telecytology, telepathology: non FDA regulated
  • Validation guidelines from CAP for WSI systems include an array of recommendations as to number of slides, components to be included (CAP: Validating Whole Slide Imaging for Diagnostic Purposes in Pathology [Accessed 8 June 2020])
    • All preparation types (cytology, IHC, FFPE H&E, etc.) should be validated using a minimum of 60 cases, plus an additional 20 cases for each additional application
    • Revalidation may be required when components are replaced, upgraded or undergo significant service
    • Validation should measure intraobserver variation, not interobserver variation and hence requires a wash out period of several weeks
  • Lab accreditation standards for WSI and telepathology included in CAP accreditation checklists
  • ATA guidelines include standards for non WSI telepathology validation and quality control
  • Medical licensure generally required in the locale where the point of patient encounter occurs for primary diagnosis but not essential for cases seen in secondary consultation
Quality control and assurance
  • Technical functioning should be ascertained regularly, at least on every day of use
  • Consideration of control of color contrast throughout the image pipeline recommended
    • Should be measured or standardized at regular intervals to optimize results
  • Professional training and validation using the technology, along with peer review, is needful
Services coding / CPT coding
  • Use the same billing codes for the service as one would use for conventional frozen section, adequacy assessment, consultation or other pathology service
  • Location coding (point of service) may or may not be required by payors
Diagrams / tables

Images hosted on other servers:

Remote consultation

Use for frozen sections at remote site


Real time high definition video demo

Board review style question #1
    Validation of a telepathology solution for remote primary sign out of surgical pathology should include at least how many cases per CAP recommendations?

  1. 30 cases for each use application
  2. 40 cases, plus 20 for each use application
  3. 60 cases, plus 20 more for each use application
  4. One week's volume of cases expected to be viewed over the system
Board review style answer #1
C. 60 cases, plus 20 more for each use application

Comment Here

Reference: Fundamentals and implementation
Board review style question #2
    Which of the following is a key measure requiring regular quality control in a telepathology system?

  1. Color consistency through the pixel pipeline
  2. Metadata retention consistency
  3. Monitor brightness
  4. Loading speed of images
  5. Scanning acquisition time
Board review style answer #2
A. Color consistency through the pixel pipeline

Comment Here

Reference: Fundamentals and implementation
Board review style question #3
    Which of the following telepathology practice settings would require prior validation?

  1. Evaluating photomicrographs of a parasite mailed to you by a colleague visiting a developing country and offering an opinion
  2. Interpreting results of flow cytometry scattergrams sent to you on an urgent case by email while away from your hospital doing an inspection
  3. Reviewing the live stream video images of a rapid on site evaluation of a pancreatic FNA procedure performed in another part of your hospital from your office as a part of your standard practice
  4. Viewing a scanned special stain digital slide sent to you by a reference laboratory in consultation and rendering an opinion for 1 patient
Board review style answer #3
C. Telepathology practice on a regular ongoing basis requires validation, while special use or infrequent consultative use would not, inasmuch as the nature and scope of the validation useful to the process could not be readily defined either in advance or perhaps even at the time. Care and caution, however, should be exercised when dealing with exceptions to the standard of validating according to intended use.

Comment Here

Reference: Fundamentals and implementation
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