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Development and preliminary evaluation of the VPS ReplaySuite: a virtual double-headed microscope for pathology
© Johnston et al; licensee BioMed Central Ltd. 2005
Received: 14 December 2004
Accepted: 21 April 2005
Published: 21 April 2005
Advances in computing and telecommunications have resulted in the availability of a range of online tools for use in pathology training and quality assurance. The majority focus on either enabling pathologists to examine and diagnose cases, or providing image archives that serve as reference material. Limited emphasis has been placed on analysing the diagnostic process used by pathologists to reach a diagnosis and using this as a resource for improving diagnostic performance.
The ReplaySuite is an online pathology software tool that presents archived virtual slide examinations to pathologists in an accessible video-like format, similar to observing examinations with a double-headed microscope. Delivered through a customised web browser, it utilises PHP (Hypertext PreProcessor) to interact with a remote database and retrieve data describing virtual slide examinations, performed using the Virtual Pathology Slide (VPS).
To demonstrate the technology and conduct a preliminary evaluation of pathologists opinions on its potential application in pathology training and quality assurance, 70 pathologists were invited to use the application to review their own and other pathologists examinations of 10 needle-core breast biopsies and complete an electronic survey. 9 pathologists participated, and all subsequently completed an exit survey.
Of those who replayed an examination by another pathologist, 83.3% (5/6) agreed that replays provided an insight into the examining pathologists diagnosis and 33.3% (2/6) reconsidered their own diagnosis for at least one case. Of those who reconsidered their original diagnosis, all re-classified either concordant with group consensus or original glass slide diagnosis. 77.7% (7/9) of all participants, and all 3 participants who replayed more than 10 examinations stated the ReplaySuite to be of some or great benefit in pathology training and quality assurance.
Participants conclude the ReplaySuite to be of some or of great potential benefit to pathology training and quality assurance and consider the ReplaySuite to be beneficial in evaluating the diagnostic trace of an examination. The ReplaySuite removes temporal and spatial issues that surround the use of double-headed microscopes by allowing examinations to be reviewed at different times and in different locations to the original examination. While the evaluation set was limited and potentially subject to bias, the response of participants was favourable. Further work is planned to determine whether use of the ReplaySuite can result in improved diagnostic ability.
Diagnostic pathology involves the classification of disease, using tissues obtained during biopsies, operations or autopsies. Classification is based on a complex set of visual features identified with the aid of a microscope. To reach a confident diagnosis, pathologists are required to possess well-developed searching, perception and classification skills, acquired with the assistance of intensive one-on-one tutoring sessions with expert pathologists. The workloads of expert pathologists, however, often restrict the frequency of these interactions.
While telepathology has yet to be incorporated into most pathology labs in a clinical role [1–4], advances in computing and telecommunications have resulted in the availability of a range of quality online training tools. Designed to supplement rather than replace human tutoring, such tools enable training pathologists to gain a wider range of educational experiences. Studies have shown the use of online training tools can improve diagnostic performance, beyond what is found with human tutoring alone [5, 6].
The majority of training tools comprise interactive tutorials that display a limited number of pre-selected images per case, often with accompanying notation [7–15]. However, as has been observed through the use of static telepathology systems for remote diagnosis, diagnostic accuracy is often dependent on appropriate field selection [16–21]. Novices often make errors when searching the slide , so the development of the skills required to locate relevant visual features are as important as those required for identifying them. Neither the searching nor identification skills utilised to reach a diagnosis are assessed by conventional quality assurance studies; diagnostic accuracy is considered the principal indicator of competence.
In contrast to static systems, virtual slides (static-dynamic hybrids) enable unrestricted examination of entire digitised tissue sections [5, 23–27]. This is a more accurate representation of the microscopic environment used by pathologists for diagnosis, and when incorporated into training tools, can provide unrestricted but supportive examining environments. With the cost and time required to digitise entire slides decreasing , virtual slides are finding greater application in pathology education [5, 22, 26].
In order to elucidate the diagnostic process of examining pathologists, the VPS (Virtual Pathology Slide), a virtual slide viewer that records diagnostic behaviour, has been developed and validated . The VPS tracks each pathologist's slide examination, recording the location of, and time spent viewing each field, and storing the data on a remote, relational database. This data is available post-examination for interrogation, potentially enabling the diagnostic technique of different pathologists to be analysed and studied. While the VPS tracks user interactions with the software, it does not utilise this data constructively to provide an intrinsic benefit to the end user, the pathologist. For this purpose, the ReplaySuite was developed.
The ReplaySuite is a web-based, user-friendly software tool that enables pathologists to replay virtual slide examinations, performed using the Virtual Pathology Slide (VPS) [23, 29, 30]. Unlike interactive tutorials and annotated virtual slides, pathologists using the ReplaySuite are able to observe the diagnostic trace of examiners, in a manner similar to the use of a double-headed microscope. This possesses significant potential for use in both pathology training, where trainee pathologists may learn from the diagnostic techniques of experts, and quality assurance, for the detection and elucidation of sources of error in participants diagnostic technique. This paper describes the development and preliminary evaluation of the ReplaySuite technology and discusses its potential applications.
Development of the ReplaySuite
Using the ReplaySuite
1. View an examination list of all examinations for a selected slide
2. View Diagnostic concordance graphs for a selected slide
3. Replay any users examination of a selected slide
Diagnostic concordance graphs
Replaying an examination
Preliminary evaluation of the ReplaySuite
A preliminary study was conducted to demonstrate the capabilities of the ReplaySuite to pathologists, and to evaluate their opinions on its use and potential application in training and quality assurance. Participants were provided with open access to the 10 needlecore biopsies examined during the VPS validation study , which they were required to examine using the VPS. Once a participant had submitted a diagnosis for a case, that participant was permitted to review their own examination data and that of other pathologists, for that slide, using the ReplaySuite. Participants who had previously participated in the VPS validation study (by examining cases) were not required to re-examine cases, and could review any examination.
Participant use of VPS and different functionality of ReplaySuite
Total examinations replayed
Own examinations replayed
Other participants examinations replayed
Diagnostic concordance graphs viewed
Examination lists viewed
Total number of functions performed
The ten needle core biopsies examined during the VPS validation study  were obtained by selecting the first breast biopsy generated each month for a ten month period from the Department of Pathology, Mater Misericordiae Hospital, Dublin, Ireland. Glass slide diagnosis (clinical diagnosis) was provided by a pathologist with a special interest in breast pathology using the Core Biopsy Reporting Guidelines for Non-operative Diagnostic Procedures and Reporting in Breast Cancer screening , as used by the British National Co-ordinating Committee for Breast Screening Pathology. Consultation was required to finalise glass slide diagnosis on some of the cases selected.
70 pathologists were invited to participate in the study. 38 Irish participants were invited with the assistance of Professor Peter Dervan, Mater Miscordiae Hospital, Dublin, and the remaining invitees comprising the 32 members of the European Working Group of Breast Screening Pathology (EWGBSP). EWGBSP members are recognised as expert breast pathologists in their native countries and all member states of the European Union (EU) are represented within the group. 17 of the 70 invited participants previously participated in the VPS validation study , 4 of which were members of the EWGBSP.
Subsequent to the study, participants completed an electronic questionnaire on their use and impressions of the software and its potential applications. Participants were asked to submit their level of agreement/disagreement with 19 statements using a Likert scale (5-point scale e.g. strongly disagree, disagree, neutral, agree, strongly agree), and answer Yes or No to a further 5 questions. A number of questions were inverted to mitigate against the well-known bias of positively phrased questions. The following are the pertinent questions asked:
Where applicable answer yes or no to the following
• Did replaying an examination by another pathologist with a diagnosis different to your own provide you with an insight into why that diagnosis was concluded?
• Did replaying examinations performed by other pathologists make you reconsider your diagnosis for any slides?
Please state how much you agree with the following statements
• The ReplaySuite is user-friendly
• The diagnostic pathway followed by the examining pathologist was apparent
• Being able to pause, fast-forward and rewind replays was useful
• The information panel was not useful
Rate the benefit of using the ReplaySuite for the following applications
• Quality Assurance
Participants were also given the opportunity to provide open-ended feedback:
• Add any further comments, or have any additional features you would like to see incorporated into the ReplaySuite.
• If yes (to the question "Did you encounter technical difficulties while using the ReplaySuite?"), please state the difficulty that occurred
Post study survey
Participants who used the ReplaySuite were resurveyed post-study in order to determine if they regularly participated in teaching. 3 questions were asked:
• Are you, or have you been involved in providing undergraduate medical training on a regular basis?
• Are you, or have you been involved in providing postgraduate pathology training on a regular basis?
• If you are not currently involved but have previously been in either activity, please state how long ago you were involved.
User participation in evaluation of ReplaySuite technology
Invited to participate
Completed electronic survey
Using the ReplaySuite
All participants who replayed at least one examination agreed or strongly agreed that the diagnostic pathway of the examining pathologist was apparent during a replay. Of the 7 participants who replayed their own or others examinations, 6 (85.71%) replayed another pathologists examination. Of these 6 participants, 5 (83.3%) agreed that it provided an insight into the examining pathologists diagnosis. Of those who replayed another's examination, 2 (33.3%) reconsidered their original diagnosis, 1 re-diagnosing concordant with group consensus and 1 re-diagnosing concordant with original glass slide diagnosis.
After originally concluding an original diagnosis of B2 (Benign) for Slide 5, User 7 replayed his/her own examination, and then replayed an examination of Slide 5 by User 6. This examination (User 6) concluded a diagnosis of B5 (Malignant), concordant with group consensus.
User 10 concluded an original diagnosis for Slide 8 of B4 (Suspicion of malignancy), which concurred with group consensus but not glass slide diagnosis, B3 (Benign but of uncertain malignant potential). User 10 replayed their own examination, then an examination of the same slide that concluded the same diagnosis by User 5. Two examinations concluding a B3 diagnosis were then replayed (Users 87 and 55), concordant with glass slide diagnosis.
Use of the VPS for diagnosis has already demonstrated "substantial" diagnostic agreement between users, 88.23% of examining pathologists obtaining a Kappa of between 0.97 and 0.65 . In determining whether pathologists could benefit from using the ReplaySuite, the primary consideration was whether participants might reassess their diagnosis as a result of observing VPS examinations of the same slides by others. In the case of 2 users, observing another's examination caused them to reconsider their original diagnosis. In contrast to the re-diagnosis of Slide 8 by User 10: B4 (suspicion of malignancy) to B3 (Benign but of uncertain malignant potential), the difference between original and secondary diagnosis of Slide 5 by User 7: B2 (benign) to B5 (malignant) is a significant re-evaluation, one which would result in significantly different courses of treatment in a clinical environment. While the degree of discordance between original diagnosis and group consensus may, in part be attributable to poor screen resolution used during examination (640 × 480 pixels), it may also be related to the relative difficulty of the case; Slide 5 achieved the second lowest group consensus (47.1%). It cannot be suggested, based on these individual examples, that group concordant re-diagnosis subsequent to ReplaySuite use will be the rule rather than the exception. However, these examples are worth noting, as it highlights the fact that using the system can result in diagnostic re-evaluation.
A number of caveats should be considered when reviewing study data, the first being small sample size. There is a significant difference between the number of pathologists invited to participate and those who completed the study (9/70). While not unique in studies involving pathologists use of telepathology systems, the small sample size may be considered a potential source of error. Bamford et al (2003) have reported similar difficulties with low participation rates , however, other studies have also attempted to evaluate telepathology tools using small sample sizes . Low participation rates may be due to a number of factors. Bamford et al (2003) cited technical difficulties and pathologists workloads as principal factors for low participation . System speed was highlighted as an issue by a number of participants during the initial VPS evaluation study . As both VPS and ReplaySuite systems utilise similar technology, speed may be a potential contributing factor to low participation rates for this follow-on study. User 36 illustrated this when asked to comment on any technical difficulties encountered during the ReplaySuite evaluation study, stating, "It took a great deal of time downloading image via dial up network connection". User 60 also commented to this effect regarding technical difficulties, commenting "very slow".
Secondly, it is not unreasonable to suggest that the positive evaluation of the ReplaySuite may in part be attributable to bias from participants (4/9) who also previously participated in the VPS validation study. Pathologists who participated in both VPS and ReplaySuite studies expressed greater satisfaction and confidence in the VPS during the VPS validation study than pathologists who participated only in the VPS study . However during the ReplaySuite study, these participants who participated in both did not provide more favourable evaluation of the ReplaySuite than participants who only participated in the ReplaySuite study. In Figure 8, the participant who considered the ReplaySuite the most user-friendly did not participate in the VPS evaluation study. In Figure 9, all participants who considered the ReplaySuite of greatest benefit in training were participants who did not participate in the VPS evaluation study, and both participants and non-participants in the VPS evaluation study considered the ReplaySuite of great benefit in quality assurance studies (Figure 10).
It also goes without question that those who participate in studies of this nature are often early adapters and often possess a positive bias towards new technology. This is an issue when evaluating any new software, and in that context, bias is unavoidable. 20 of the 70 participants invited to participate had foreknowledge of the VPS, however none, had previously seen the ReplaySuite and, therefore, had no preconceived notions about the software.
The concept of a virtual double-headed microscope is not new , however previous references to such concepts utilised video-conferencing that was dependent on the presence of an expert. While both pathologists were not required to be present at the same location, they were required to be available at the same time. In contrast, archived VPS examinations are available at any time at any location, irrespective of expert availability. Unlike real-time observation of examinations, the ReplaySuite permits examinations to be paused, fast-forwarded and rewound, and images may be annotated, providing a description of visual features within the field of view.
The benefits of various online tools and their impact on diagnostic performance have already been highlighted, however the ReplaySuite possesses a number of practical advantages. Many online tools present the diagnostic opinion of one pathologist. In contrast, the ReplaySuite can replay examinations of the same slide by multiple experts, illustrating a number of different diagnostic pathways that corroborate the same diagnostic hypothesis. Alternatively, reviewing pathologists may observe examinations that disagreed with group consensus, in order to identify the possible sources of disagreement. This is of particular interest for disorders that suffer from a high degree of inter-observer variability. Additionally, interactive tutorials and annotated virtual slides require considerable time to create, however, individual authoring time with the VPS/ReplaySuite is around 6 minutes, per user, per slide.
Figures 9 &10 illustrate that the more participants used the system, the greater potential benefit they perceived it having in pathology training and quality assurance. All 3 participants (Users 10,55,74) who replayed more than ten examinations considered the ReplaySuite of some or of great potential benefit in pathology training and quality assurance. While small sample size precludes the significance of a relationship between heavy use and favourable perception, it is not unreasonable to suggest that participants who fully appreciate the capabilities of the ReplaySuite will possess a more considered opinion.
The objective of the study was to develop the ReplaySuite technology, and to assess the opinions of pathologists on its use and potential application. Participants concluded the ReplaySuite to be of some or of great potential benefit to pathology training and quality assurance and considered the ReplaySuite to be beneficial in evaluating the diagnostic trace of an examination. Future evaluation of the ReplaySuite in a larger quality assurance study and training environment is anticipated.
One-to-one human tutoring remains, and will remain for the foreseeable future, the pre-eminent means of nurturing pathologist's diagnostic skills. However, as factors such as expert availability and case diversity vary, from institution to institution, it is impossible to replicate the same training environment universally. Supplementary online training tools may well help to redress the balance, providing wide access to expert pathologists and a diverse range of cases from multiple institutions, enabling an educational diversity often unachievable in a single institution. The ReplaySuite is a unique tool that permits pathologists to learn from multiple experts in a manner not possible with current tools.
The Authors would like to thank the Health Research Board, Ireland for their funding, and the pathologists who participated in this study.
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