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Use of whole slide imaging (WSI) for distance teaching
  1. Andrew John Evans1,
  2. Nadia Depeiza2,
  3. Shara-Gaye Allen1,
  4. Kimone Fraser2,
  5. Suzanne Shirley2,
  6. Runjan Chetty1
  1. 1 Department of Pathology, University Health Network Laboratory Medicine Program, University of Toronto, Toronto, Ontario, Canada
  2. 2 Pathology, University of the West Indies at Mona, Mona, Saint Andrew, Jamaica
  1. Correspondence to Professor Runjan Chetty, Department of Histopathology, Brighton and Sussex University Hospitals, Eastern Road, Brighton, BN5 2EE, UK; runjan.chetty{at}


Background Time, travel and financial constraints have meant that traditional visiting teaching engagements are more difficult to accomplish. This has been exacerbated with the advent of the COVID-19 pandemic. The use of digital pathology and whole slide imaging (WSI) as an educational tool for distance teaching is underutilised and not fully exploited. This paper highlights the utility and feedback on the use of WSI for distance education/teaching.

Materials and methods Building on an existing relationship with the University of the West Indies (UWI), pathologists at University Health Network, Toronto, provided distance education using WSI, a digitised slide image hosting repository and videoconferencing facilities to provide case-based teaching to 15 UWI pathology trainees. Feedback was obtained from residents via a questionnaire and from teachers via a discussion.

Results There was uniform support from teachers who felt that teaching was not hampered by the ‘virtual’ engagement. Comfort levels grew with each engagement and technical issues with sound diminished with the use of a portable speaker. The residents were very supportive and enthusiastic in embracing this mode of teaching. While technical glitches marred initial sessions, the process evened out especially when the slide hosting facility, teleconferencing and sound issues were changed.

Conclusions There was unanimous endorsement that use of WSI was the future, especially for distance teaching. However, it was not meant to supplant the use of glass slides in their current routine, daily practice.

  • whole slide imaging
  • digital pathology
  • distance learning
  • pathology education
  • COVID-19

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Training in histopathology or anatomical pathology has been considered by many an apprenticeship that can best be accomplished sitting at a microscope and viewing glass slides with a preceptor. While there still is merit in this hallowed, time-honoured method of teaching, it is restrictive in terms of exposure to a variety of other teachers especially from other countries. The standard tools of education are textbooks, glass slides and light microscopy, but in the last 20 years or so, web-based or electronic resources have been implemented to supplement and/or replace these more traditional learning modalities.1–5 Indeed, a Digital School of Pathology was set up in 2017 with a proposed syllabus.6 In their review of future-proofing pathology, Williams et al highlighted the whole slide image (WSI) in enhancing teaching, training and mentoring.7 Furthermore, several organisations, such as the College of American Pathologists and the Royal College of Pathologists have endorsed digital pathology as a possible method of reporting clinical cases, training, education and research.

Visiting or travelling lectureships are still in vogue and still have a role to play in education in a broader remit. The ability to engage with visiting teachers in one on one learning not only helps to hone one’s diagnostic skills but also facilitates a broader approach to the specialty, and thus, is an important and indeed, invaluable learning opportunity. The drawbacks of inviting experts to teach include: time, availability and expense incurred due to travel, accommodation and other subsistence costs.

One of the authors (AJE) has a longstanding relationship with the Department of Pathology at the University of West Indies, Mona campus, Jamaica, as an external examiner. Building on this relationship, he was asked to provide trainee teaching remotely.

The purpose of this paper is to highlight the practicalities of setting up remote teaching, and to provide learner feedback (by way of a survey) to the use of WSIs, including the technology challenges experienced.

Materials and methods

Teaching Session Workflow: 3 subspecialty pathologists at University Health Network (UHN) in Toronto (AJE, S-GA and RC) selected teaching cases. These sessions were intended primarily to engage the UWI residents in discussions on a diagnostic approach to cases that varied in terms of difficulty, as opposed to those for which ‘spot’ diagnoses could be provided. Each teaching session in the pilot period included 5–7 separate cases and was set up according to a particular subspecialty area—namely genitourinary, breast, gynaecological or gastrointestinal pathology. One resident (ND/KF) tested the process as a recipient.

One representative deidentified H&E slide from each case was scanned at UHN at 20× (0.5 μm/pixel resolution) using a Leica AT2 Turbo scanner equipped with a 20 ×/0.75 Plan Apo objective. The resulting digital files ranged in size from 25 MB to 625 MB. The digital files were sent to the senior resident at UWI (ND or KF) roughly 1 week in advance of the distance teaching session using two different methods. The scanned slides were initially sent using the UHN institutional file share system, which had an upper limit of 800 MB per individual file share. The digital slides were then downloaded onto a computer in the residents’ room at UWI where they could be reviewed by all residents in advance of the session. While the UHN file share method (first iteration of the teaching) successfully transmitted the slides, the size limit of the system created limitations on the type of slides that could be selected. Those requiring fine detail and scanned at 40 × generated large images which were above the 800 MB limit for sharing. It also required cases to be sent to UWI in multiple batches for each teaching session. After four distance teaching sessions using the file share mechanism, scanned slides were then shared with the UWI residents using PathPresenter ( in a second iteration of the process. The UHN pathologist was able to share a single PathPresenter folder with the Senior Resident, who in turn shared it with the residents. This method was particularly advantageous for sessions held during the COVID-19 pandemic as the UWI residents were present in multiple locations inside and outside of Jamaica.

The actual teaching sessions consisted of video teleconferences, initially conducted using Google Hangouts (four sessions) and subsequently, using Microsoft (MS) Teams (three sessions). The latter format was supplemented using a portable conferencing Bluetooth speaker (Jabra GN Speak 510). All residents were seated together in front of a single monitor for the teaching session, except for during the COVID-19 pandemic, when they participated on different devices with the prerequisite distancing maintained. The senior resident (ND/KF) was charged with reviewing the scanned slides and assigning the cases to residents based on degree of difficulty and level of training of the individual resident. The individual resident used their own computer desktop facilities to view the cases before the group teaching session. The designated resident served as the discussant for their assigned case; however, all residents were encouraged to participate in the discussion. The discussant was asked to describe salient features on the slide, integrate findings into clinical history and provide most likely diagnosis if possible or a differential diagnosis. This was best enabled in sessions using PathPresenter where the residents were able to ‘drive’ or navigate the virtual slides. Residents were encouraged to ask the UHN teachers for additional clinical information when required. They were also asked to provide their approach to further diagnostic workup using special stains, immunohistochemistry or molecular diagnostics. The UHN teachers were familiar with the fact that access to ancillary diagnostic techniques is a limiting factor at UWI, with cases requiring additional workup being sent abroad at patient expense. As such, another goal of the teaching sessions was to underscore the types of diagnoses that would ideally require ancillary testing to optimise patient care.

At the end of the trial period, a questionnaire was designed to ascertain trainee evaluation and feedback on the process and learning experience (see box 1). Six multipart questions and a free comment section were provided to assist with response evaluation.

Box 1

Resident questionnaire on the use of digital slides and distance teaching

  1. Level of training

    1. Postgraduate year (PGY) 1

    2. PGY 2

    3. PGY 3

    4. PGY 4

    5. PGY 5

  2. Concept of using whole slide imaging (WSI)

    1. I agree with the concept as this is the way forward: yes/no

    2. I agree with reservations: yes/no. Please comment on reservations

    3. It is premature as a learning tool and I prefer traditional glass slide teaching on a microscope: yes/no


  3. Logistics and practicalities around use of WSI

    1. The process was slow and frustrating first/second iteration: yes/no/sometimes

    2. The process worked seamlessly most of the time with little or no technical glitches first/second iteration: yes/no

    3. A lot more preparatory work was needed compared with glass slide review: yes/no


  4. As regards image quality

    1. The images were superior to glass slides: yes/no

    2. The images were as good as glass slides: yes/no

    3. Images were inferior to glass slides: yes/no


  5. How has using WSI impacted on your training?

    1. Minimally as it only allows distance teaching to occur: yes/no

    2. Has made a significant only in restricted settings: yes/no

    3. All training should use WSI rather than glass slides if possible: yes/no


  6. Personal experience with WSI and electronic learning tools

    1. I used WSI as part of medical school training in pathology: yes/no

    2. I acquired experience myself as a pathology trainee from various sources: yes/no

    3. This was my first experience of using WSI: yes/no


  7. Suggestions on how distance teaching by WSI could be improved


Each session lasted from 60 min to 75 min. The web camera allowed the preceptor to engage in directed dialogue with every resident who introduced themselves and their level of training.

Teachers’ perspective

Preparation for the teaching session using WSI compared favourably with preparation required for teaching with glass slides. The main issue identified was the size limit of the UHN file share system which created limitations on the slides that could be selected. This also affected scanning at higher magnification (×40), which would allow for demonstration of more detailed histological features. The use of PathPresenter proved to be more efficient, despite the fact that the length of time for uploading digital slides was longer when compared with the UHN file share.

The initial sessions were marred by poor sound quality with frequent dropping of the line. The trainees could hear the preceptor well but sound quality from the residents was not optimal. However, this improved once trainees could get closer to the microphone. There was even further improvement with the acquisition and use of the Bluetooth conference speaker which provided consistently good sound quality throughout the session. There was an unavoidable time lag for sound to travel but this did not prevent engagement occurring almost in real time. There were no issues with image quality from the teachers’ point of view as the WSI were on their desktop allowing for manipulation. There was minimal lag time when images were moved by the teacher. Resolution and image quality was consistently good.

Once the initial technical and distance engagement impediments were overcome, the sessions proceeded smoothly and all teachers enjoyed the experience, convenience and facility provided by WSI, especially the second iteration of the teaching sessions.

Each case concluded with a discussion on the final diagnosis and requirements for issuing a complete report to facilitate patient care. Common histological prognostic factors, margin assessment, pathological staging, molecular diagnostics and the possible need for screening of family members were discussed when relevant. Following each session, UHN teachers sent papers in portable document format (PDF) as suggested further reading concerning the points discussed for each case. All of the aforementioned educational material could then be archived as an independent study resource for current and future residents at UWI.

Trainees’ perspective

See table 1. Fifteen trainees responded to the survey. Three trainees were postgraduate year (PGY) 1, 3 PGY 2, 4 PGY 3, 2 PGY 4 and 3 PGY5. As regards the concept of using WSI as a means of learning 11 thought it was the way forward without any reservations, while 4 agreed with reservations. The reservations included: a role for both glass slides and WSI in training/teaching, 1 felt glass slides were easier to read, another felt that they preferred glass slides for personal use although WSI was great for distance learning, consults and teaching large groups. One commented that WSI is not universal and the ‘art of microscopy using glass slides should still be learned’.

Table 1

Responses of trainees to the questionnaire

In terms of the logistics and practical issue surrounding the use of WSI in the first phase of implementation, eight felt that it worked seamlessly with no glitches, while seven found the process slow and frustrating sometimes. Once the format of hosting the slides, the teleconferencing set-up and addition of a portable conferencing speaker was added (‘second iteration’), all 15 residents felt the process worked seamlessly with minimal if any glitches. As for the image quality achieved by WSI, 3 thought they were superior to glass slides and the remaining 12 thought that WSI was as good as the glass slides.

When assessing the impact of WSI on training: six trainees felt that it was minimal as it only facilitated distance teaching, eight felt that it did have a significant impact but only in restricted training settings, and one thought that WSI should be used in preference to glass slides for all forms of microscopy training.

An interesting aspect of the responses was that this was the first experience using WSI for 14 of the 15 respondents. Only one had acquired experience from other online training resources.

The free comments included suggestions that all cases should be routinely scanned at ×40, the need for better internet connectivity, more interactive sessions, a mixture of didactic lectures using WSI rather than only slide sessions, cases should be more pertinent to pathology seen locally and easier access to more universal software and secure password-protected websites.


Distance teaching using WSI will grow into a mainstream mode of pathology teaching, something that has been reinforced by the shadow cast over the world by COVID-19, a shadow that is likely to endure for a considerable period of time. The teaching engagement with UWI provided an ideal example of the potential opportunities of accomplishing distance learning and teaching using WSI. By the same token, as with new, disruptive technologies, there is a learning curve and in many instances it is an iterative process to achieve the ideal state. The latter is best exemplified by the use of different hosting resources such as MS teams and a dedicated image repository (PathPresenter) which facilitated trainee access to slides. The addition of a portable Bluetooth videoconferencing speaker enhanced sound quality with no background noise or reverberations. The initial difficulties encountered by residents in viewing the uploaded images was based on the connectivity and specifications their own individual computers. However, this was largely overcome by implementing a better hosting and videoconferencing set-up. It is worth examining the logistics and set-up on a trial basis for multiple users rather than one or two who may have better internet connectivity.

There are several obvious and clear advantages to using WSI rather than glass slides. Scanning of the original glass slide allows for dissemination of a faithfully reproduced replica of the slide without having to resort to cutting more sections (which may not necessarily be representative of the original slide/pathology), depletion of a tissue block which is vital for ancillary studies that often impact on patient care, obviating the need for packaging and posting slides, the possibilities of glass slide breakage and delays/losses in transit and, the time and cost savings. WSI provides the trainees and teachers with the opportunity to visualise the slide in real time despite geographical separation, notwithstanding some technical issues. The latter ability enhances and indeed facilitates distance teaching as glass slides will not afford the ability of both parties to visualise the slide simultaneously. Thus, the advantages of using WSI are numerous and far outweigh disadvantages.

The major cons to WSI use for training are centred on connectivity issues. While some sound problems emanated from the initial teaching sessions, these were quickly smoothed out. Having host bandwidth to allow for smooth and seamless manipulation of the slide is imperative. Much of the frustration experienced by trainees centred on the process being slow. These issues can be resolved with better connectivity which will be a natural consequence of evolving global networks such as 5G.

This experience proves that a good teaching experience can be achieved through deployment of WSI. We are aware that at the moment the routine ‘currency’ in pathology departments is the glass slide. However, the adoption of digital workflow solutions means that a greater proportion of departments will have WSI available for teaching purposes. The cost of scanners (high and low throughput) is within the means of several departments, especially those with teaching responsibilities. So while scanning of routine cases may not occur, slides can be scanned specifically for teaching purposes.

This paper highlights the successful implementation of distance teaching using WSI. Both teachers and trainees reported satisfaction with this mode of teaching overall, despite initial and some ongoing but diminishing technical issues. The latter were not insurmountable and did not detract from the utility and value of WSI as a teaching mode.

Take home messages

  • Whole slide imaging (WSI) has valuable role in distance teaching.

  • Residents are increasingly comfortable using WSI for primary viewing and diagnostic purposes.

  • WSI, a user-friendly image repository and good videoconferencing/sound facilities, makes the process seamless and enjoyable for trainees and teachers.

  • Careful planning and testing of the set-up are essential before ‘going live’.

  • This form of teaching is equally adept for local teaching as it is for distance teaching in the era of COVID-19.

Ethics statements



  • Handling editor Dhirendra Govender.

  • Twitter @runjanchetty

  • Contributors All authors contributed to the concept, collation of data and writing of the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Commissioned; externally peer reviewed.