Virtual microscopy for histology quality assurance of screen-detected polyps

Whole slide imaging equivalency and efficiency study: experience at a large academic center

Whole slide imaging is Food and Drug Administration-approved for primary diagnosis in the United States of America; however, relatively few pathology departments in the country have fully implemented an enterprise wide digital pathology system enabled for primary diagnosis. Digital pathology has significant potential to transform pathology practice with several published studies documenting some level of diagnostic equivalence between digital and conventional systems. However, whole slide imaging also has significant potential to disrupt pathology practice, due to the differences in efficiency of manipulating digital images vis-à-vis glass slides, and studies on the efficiency of actual digital pathology workload are lacking. Our randomized, equivalency and efficiency study aimed to replicate clinical workflow, comparing conventional microscopy to a complete digital pathology signout using whole slide images, evaluating the equivalency and efficiency of glass slide to whole slide image reporting, reflective of true pathology practice workloads in the clinical setting. All glass slides representing an entire day's routine clinical signout workload for six different anatomic pathology subspecialties at Memorial Sloan Kettering Cancer Center were scanned on Leica Aperio AT2 at ×40 (0.25 µm/pixel). Integration of whole slide images for each accessioned case is through an interface between the Leica eSlide manager database and the laboratory information system, Cerner CoPathPlus. Pathologists utilized a standard institution computer workstation and viewed whole slide images through an internally developed, vendor agnostic whole slide image viewer, named the "MSK Slide Viewer". Subspecialized pathologists first reported on glass slides from surgical pathology cases using routine clinical workflow. Glass slides were de-identified, scanned, and re-accessioned in the laboratory information system test environment. After a washout period of 13 weeks, pathologists reported the same clinical workload using whole slide image integrated within the laboratory information system. Intraobserver equivalency metrics included top-line diagnosis, margin status, lymphovascular and/or perineural invasion, pathology stage, and the need to order ancillary testing (i.e., recuts, immunohistochemistry). Turnaround time (efficiency) evaluation was defined by the start of each case when opened in the laboratory information system and when the case was completed for that day (i.e., case sent to signout queue or pending ancillary studies). Eight pathologists participated from the following subspecialties: bone and soft tissue, genitourinary, gastrointestinal, breast, gynecologic, and dermatopathology. Glass slides signouts comprised of 204 cases, encompassing 2091 glass slides; and digital signouts comprised of 199 cases, encompassing 2073 whole slide images. The median whole slide image file size was 1.54 GB; scan time/slide, 6 min 24 s; and scan area 32.1 × 18.52 mm. Overall diagnostic equivalency (e.g., top-line diagnosis) was 99.3% between digital and glass slide signout; however, signout using whole slide images showed a median overall 19% decrease in efficiency per case. No significant difference by reader, subspecialty, or specimen type was identified. Our experience is the most comprehensive study to date and shows high intraobserver whole slide image to glass slide equivalence in reporting of true clinical workflows and workloads. Efficiency needs to improve for digital pathology to gain more traction among pathologists.

The Empirical Foundations of Telepathology: Evidence of Feasibility and Intermediate Effects

INTRODUCTION

Telepathology evolved from video microscopy (i.e., "television microscopy") research in the early 1950s to video microscopy used in basic research in the biological sciences to a basic diagnostic tool in telemedicine clinical applications. Its genesis can be traced to pioneering feasibility studies regarding the importance of color and other image-based parameters for rendering diagnoses and a series of studies assessing concordance of virtual slide and light microscopy diagnoses. This article documents the empirical foundations of telepathology.

METHODS

A selective review of the research literature during the past decade (2005-2016) was conducted using robust research design and adequate sample size as criteria for inclusion.

CONCLUSIONS

The evidence regarding feasibility/acceptance of telepathology and related information technology applications has been well documented for several decades. The majority of evidentiary studies focused on intermediate outcomes, as indicated by comparability between telepathology and conventional light microscopy. A consistent trend of concordance between the two modalities was observed in terms of diagnostic accuracy and reliability. Additional benefits include use of telepathology and whole slide imaging for teaching, research, and outreach to resource-limited countries. Challenges still exist, however, in terms of use of telepathology as an effective diagnostic modality in clinical practice.

Diagnostic reproducibility of tumour budding in colorectal cancer: a multicentre, multinational study using virtual microscopy

AIMS

Despite the established prognostic relevance of tumour budding in colorectal cancer, the reproducibility of the methods reported for its assessment has not yet been determined, limiting its use and reporting in routine pathology practice.

METHODS AND RESULTS

A morphometric system within telepathology was devised to evaluate the reproducibility of the various methods published for the assessment of tumour budding in colorectal cancer. Five methods were selected to evaluate the diagnostic reproducibility among 10 investigators, using haematoxylin and eosin (H&E) and AE1-3 cytokeratin-immunostained, whole-slide digital scans from 50 pT1-pT4 colorectal cancers. The overall interobserver agreement was fair for all methods, and increased to moderate for pT1 cancers. The intraobserver agreement was also fair for all methods and moderate for pT1 cancers. Agreement was dependent on the participants' experience with tumour budding reporting and performance time. Cytokeratin immunohistochemistry detected a higher percentage of tumour budding-positive cases with all methods compared to H&E-stained slides, but did not influence agreement levels.

CONCLUSION

An overall fair level of diagnostic agreement for tumour budding in colorectal cancer was demonstrated, which was significantly higher in early cancer and among experienced gastrointestinal pathologists. Cytokeratin immunostaining facilitated detection of budding cancer cells, but did not result in improved interobserver agreement.

The Diagnostic Concordance of Whole Slide Imaging and Light Microscopy: A Systematic Review

CONTEXT

-Light microscopy (LM) is considered the reference standard for diagnosis in pathology. Whole slide imaging (WSI) generates digital images of cellular and tissue samples and offers multiple advantages compared with LM. Currently, WSI is not widely used for primary diagnosis. The lack of evidence regarding concordance between diagnoses rendered by WSI and LM is a significant barrier to both regulatory approval and uptake.

OBJECTIVE

-To examine the published literature on the concordance of pathologic diagnoses rendered by WSI compared with those rendered by LM.

DATA SOURCES

-We conducted a systematic review of studies assessing the concordance of pathologic diagnoses rendered by WSI and LM. Studies were identified following a systematic search of Medline (Medline Industries, Mundelein, Illinois), Medline in progress (Medline Industries), EMBASE (Elsevier, Amsterdam, the Netherlands), and the Cochrane Library (Wiley, London, England), between 1999 and March 2015.

CONCLUSIONS

-Thirty-eight studies were included in the review. The mean diagnostic concordance of WSI and LM, weighted by the number of cases per study, was 92.4%. The weighted mean κ coefficient between WSI and LM was 0.75, signifying substantial agreement. Of the 30 studies quoting percentage concordance, 18 (60%) showed a concordance of 90% or greater, of which 10 (33%) showed a concordance of 95% or greater. This review found evidence to support a high level of diagnostic concordance. However, there were few studies, many were small, and they varied in quality, suggesting that further validation studies are still needed.

Validation of Whole-Slide Imaging for Histolopathogical Diagnosis: Current State

Rapid advances in informatics and technological improvements have led to the development of high-throughput whole-slide imaging (WSI) scanners able to produce high-quality digital images, which allow achieving a correct diagnosis of the biopsies using virtual viewers. This technology is currently prepared to be introduced in the departments of pathology for routine diagnosis. The aim of this review is to analyze the current evidence regarding the use of WSI in primary or routine diagnosis in the different subspecialties of pathology. An increasing number of studies have shown almost perfect inter- and intraobserver agreement between the diagnoses obtained with WSI and the classical diagnoses based on conventional light microscopy. The only exception seems to be cytology, which still requires some technological development. Although validation studies are needed in some areas of pathology, growing evidence indicates that WSI is a reliable tool for routine diagnosis. Pathologists have a positive perception of the ergonomics of the workstations, the low magnification of WSI and the possibility of making annotations and measurements. WSI can be used from any device and anywhere, thereby providing great opportunities for teleconsultation. New technologies such as the recognition of histopathology patterns using image analysis may facilitate diagnosis and improve the reproducibility among pathologists in the future.

Digital slide viewing for primary reporting in gastrointestinal pathology: a validation study

Despite the increasing availability of digital slide viewing, and numerous advantages associated with its application, a lack of quality validation studies is amongst the reasons for poor uptake in routine practice. This study evaluated primary digital pathology reporting in the setting of routine subspecialist gastrointestinal pathology, commonplace in most tissue pathology laboratories and representing one of the highest volume specialties in most laboratories. Individual digital and glass slide diagnoses were compared amongst three pathologists reporting in a gastrointestinal subspecialty team, in a prospective series of 100 consecutive diagnostic cases from routine practice in a large teaching hospital laboratory. The study included a washout period of at least 6 months. Discordant diagnoses were classified, and the study evaluated against recent College of American Pathologists (CAP) recommendations for evaluating digital pathology systems for diagnostic use. The study design met all 12 of the CAP recommendations. The 100 study cases generated 300 pairs of diagnoses, comprising 100 glass slide diagnoses and 100 digital diagnoses from each of the three study pathologists. 286 of 300 pairs of diagnoses were concordant, representing intraobserver concordance of 95.3 %, broadly comparable to rates previously published in this field. In ten of the 14 discordant pairs, the glass slide diagnosis was favoured; in four cases, the digital diagnosis was favoured, but importantly, the 14 discordant intraobserver diagnoses were considered to be of minor clinical significance. Interobserver, or viewing modality independent, concordance was found in 94 of the total of 100 study cases, providing a comparable baseline discordance rate expected in any second viewing of pathology material. These overall results support the safe use of digital pathology in primary diagnostic reporting in this setting.

Virtual microscopy system at Chinese medical university: an assisted teaching platform for promoting active learning and problem-solving skills

BACKGROUND

Chinese medical universities typically have a high number of students, a shortage of teachers and limited equipment, and as such histology courses have been taught using traditional lecture-based formats, with textbooks and conventional microscopy. This method, however, has reduced creativity and problem-solving skills training in the curriculum. The virtual microscope (VM) system has been shown to be an effective and efficient educational strategy. The present study aims to describe a VM system for undergraduates and to evaluate the effects of promoting active learning and problem-solving skills.

METHODS

Two hundred and twenty-nine second-year undergraduate students in the Third Military Medical University were divided into two groups. The VM group contained 115 students and was taught using the VM system. The light microscope (LM) group consisted of 114 students and was taught using the LM system. Post-teaching performances were assessed by multiple-choice questions, short essay questions, case analysis questions and the identification of structure of tissue. Students' teaching preferences and satisfaction were assessed using questionnaires.

RESULTS

Test scores in the VM group showed a significant improvement compared with those in the LM group (p < 0.05). There were no substantial differences between the two groups in the mean score rate of multiple-choice questions and the short essay category (p > 0.05); however, there were notable differences in the mean score rate of case analysis questions and identification of structure of tissue (p < 0.05). The questionnaire results indicate that the VM system improves students' productivity and promotes learning efficiency. Furthermore, students reported other positive effects of the VM system in terms of additional learning resources, critical thinking, ease of communication and confidence.

CONCLUSIONS

The VM system is an effective tool at Chinese medical university to promote undergraduates' active learning and problem-solving skills as an assisted teaching platform.

The natural history of colorectal adenomas and early cancer

Adenomas represent the morphological precursors of the vast majority of colorectal cancers: although every adenoma has the capacity of malignant evolution, most adenomas stabilize their progression or even regress. Pathological factors are predictive of the natural history of adenomas in terms of potential and time interval for becoming malignant. Regression of adenomas is histologically well established, but it is thought to be a dynamic process, with cycling phases of regression and growth. Colorectal carcinoma invading the submucosa but not the muscular layer represents the earliest form of clinically relevant colorectal cancer. Grade of differentiation of carcinoma, lymphovascular invasion, and state of the resection margin predict the risk of metastasis. Microstaging of invasive cancer together with tumuor budding allow the metastatic risk to be further stratified into minimal, low, and high. Two distinct profiles are identifiable in the natural history of cancerous adenomas: blocking the growth of early cancer and allowing its progression towards advanced cancer. Thus, biomarkers to distinguish between progressive and non-progressive pT1 neoplasia are needed.

The evaluation of colon biopsies using virtual microscopy is reliable

AIMS

Virtual microscopy offers major advantages for pathology practice, separating slide evaluation from slide production. The aim of this study was to investigate the reliability of using whole slide images as compared with routine glass slides for diagnostic purposes.

METHODS AND RESULTS

Colon biopsies (n = 295) were assessed using both glass slides and whole slide images by four pathologists and two residents. Two pathologists scored the digital images of biopsies in a primary diagnostic setting. For each case, the consensus diagnosis was defined as the majority diagnosis on the study's glass slides. All diagnoses were grouped into seven main diagnostic categories, and further divided into subgroups. The overall concordance rates were 89.6% for whole slide images and 91.6% for light microscopy. The concordance rates of the subgroups 'adenoma' and 'adenocarcinoma' between whole slide images and conventional microscopy showed only small variability. The intraobserver (whole slide images versus glass slide) agreement, including subgroups, was substantial, with a mean κ-value of 0.78, and was higher than the interobserver agreement for glass slides (interobserver κ-value of 0.69).

CONCLUSIONS

This study shows good diagnostic accuracy and reproducibility for virtual microscopy, indicating that this technology can reliably be used for pathological evaluation of colon biopsies in a primary clinical setting.

HistoViewer: an interactive e-learning platform facilitating group and peer group learning

Understanding tissue architecture and the morphological characteristics of cells is a central prerequisite to comprehending the basis of physiological tissue function in healthy individuals and relating this to disease states. Traditionally, medical curricula include courses where students examine glass slides of cytological or tissue samples under a light microscope. However, it is challenging to implement group and peer group learning in these courses and to give students sufficient time to study specimens. An increasing number of medical schools have thus started to implement digital slide viewers, so-called virtual microscopes, in histology and histopathology. These websites are mostly based on standard commercial software and offer limited adaptation to the special needs of first-year students. An e-learning platform has therefore been developed for use in cytology and histology courses. This virtual microscopy tool is coupled to a central database in which students can label and store the positions of individual structures for later repetition. As learning in pairs and peer groups has been shown to provide a high learning outcome, identified structures can be shared and discussed with students' peers or faculty via a built-in communication module. This website has the possibility of opening an arbitrary number of frames which all can actively be moved and changed in magnification to enable the comparison of specimens and thus encourage a more global understanding of related tissues. HistoViewer is thus suggested as an e-learning tool combining several modern teaching concepts.

Digital slide images for primary diagnostics in breast pathology: a feasibility study

Digital slide images have been used in many areas of pathology such as teaching, research, digital archiving, teleconsultation, and quality assurance testing. However, they have not much been used as yet for upfront diagnostics. The aim of this study was therefore to test the feasibility of digital slide image-based diagnosis of breast specimens. Sections of 100 breast specimens previously diagnosed conventionally were scanned and rediagnosed on digital slide images by the same pathologists who performed the initial light microscopy-based diagnosis. The digital slide image diagnoses were compared with the light microscopy diagnoses and classified as concordant, slightly discrepant (without clinical or prognostic consequences), or discrepant. The original light microscopy- and digital slide image-based diagnoses were concordant in 93% and slightly discrepant in 6% of cases. There was only 1 discrepant case with clinical or prognostic implication to the patient. However, for this case, no final agreement could be achieved. For 4 of the 6 slightly discrepant cases, digital slide image diagnosis was considered the better one, whereas the original diagnosis was preferred in only 1 case. In addition, for 1 case categorized as slightly discrepant, both the digital slide image and conventional diagnosis were imperfect according to 2 reviewing breast pathologists. This study demonstrates that upfront histopathologic diagnosis of breast biopsies and resections can reliably be done on digital slide image.

Comparing virtual with conventional microscopy for the consensus diagnosis of Barrett's neoplasia in the AspECT Barrett's chemoprevention trial pathology audit

AIMS

To compare the diagnostic accuracy of conventional versus virtual microscopy for the diagnosis of Barrett's neoplasia.

METHODS AND RESULTS

Sixty-one biopsies from 35 ASPirin Esomeprazole ChemopreventionTrial (AspECT) trial patients were given a Barrett's neoplasia score (1-5) by a panel of five pathologists using conventional microscopy. Thirty-three biopsies positive for neoplasia were digitized and rescored blindly by virtual microscopy. Diagnostic reliability was compared between conventional and virtual microscopy using Fleiss' kappa. There was substantial reliability of diagnostic agreement (κ = 0.712) scoring the 61 biopsies and moderate agreement scoring the subgroup of 33 'positive' biopsies with both conventional microscopy (κ = 0.598) and virtual microscopy (κ = 0.436). Inter-observer diagnostic agreement between two pathologists by virtual microscopy was substantial (κ = 0.76). Comparison of panel consensus neoplasia scores between conventional and virtual microscopy was almost perfect (κ = 0.8769). However, with virtual microscopy there was lowering of the consensus neoplasia score in nine biopsies.

CONCLUSIONS

Diagnostic agreement with virtual microscopy compares favourably with conventional microscopy in what is recognized to be a challenging area of diagnostic practice. However, this study highlights possible limitations for this method in the primary diagnostic setting.

Quality assurance in pathology in colorectal cancer screening and diagnosis—European recommendations

In Europe, colorectal cancer is the most common newly diagnosed cancer and the second most common cause of cancer deaths, accounting for approximately 436,000 incident cases and 212,000 deaths in 2008. The potential of high-quality screening to improve control of the disease has been recognized by the Council of the European Union who issued a recommendation on cancer screening in 2003. Multidisciplinary, evidence-based European Guidelines for quality assurance in colorectal cancer screening and diagnosis have recently been developed by experts in a pan-European project coordinated by the International Agency for Research on Cancer. The full guideline document consists of ten chapters and an extensive evidence base. The content of the chapter dealing with pathology in colorectal cancer screening and diagnosis is presented here in order to promote international discussion and collaboration leading to improvements in colorectal cancer screening and diagnosis by making the principles and standards recommended in the new EU Guidelines known to a wider scientific community.