Do we truly see what we think we see? The role of cognitive bias in pathological interpretation

In the histomorphological grading of prostate carcinoma, pathologists have regularly assigned comparable scores for the architectural Gleason and the now‐obsolete nuclear World Health Organization (WHO) grading systems. Although both systems demonstrate good correspondence between grade and survival, they are based on fundamentally different biological criteria. We tested the hypothesis that this apparent concurrence between the two grading systems originates from an interpretation bias in the minds of diagnostic pathologists, rather than reflecting a biological reality. Three pathologists graded 178 prostatectomy specimens, assigning Gleason and WHO scores on glass slides and on digital images of nuclei isolated out of their architectural context. The results were analysed with respect to interdependencies among the grading systems, to tumour recurrence (PSA relapse > 0.1 ng/ml at 48 months) and robust nuclear morphometry, as assessed by computer‐assisted image analysis. WHO and Gleason grades were strongly correlated (r = 0.82) and demonstrated identical prognostic power. However, WHO grades correlated poorly with nuclear morphology (r = 0.19). Grading of nuclei isolated out of their architectural context significantly improved accuracy for nuclear morphology (r = 0.55), but the prognostic power was virtually lost. In conclusion, the architectural organization of a tumour, which the pathologist cannot avoid noticing during initial slide viewing at low magnification, unwittingly influences the subsequent nuclear grade assignment. In our study, the prognostic power of the WHO grading system was dependent on visual assessment of tumour growth pattern. We demonstrate for the first time the influence a cognitive bias can have in the generation of an error in diagnostic pathology and highlight a considerable problem in histopathological tumour grading. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Progression in diagnostic pathology; development of virtual microscopy and its applications

Many systems have already been designed and successfully used for clinical laboratory and pathological examination. The evolution of image analysis was enabled when analog images of the original glass slides could be transferred to digital images with the rapid development of virtual microscopy and virtual slides depended upon computer technologies. Today, whole slide can be acquired by virtual microscopes. The applications of virtual microscopy and virtual slides for teaching, diagnosis, telepathology, and research are more widely used than those of real microscope and real glass slides. In traditional cancer diagnosis, pathologists examine biopsies to make diagnostic assessments largely based on two-dimensional cell morphology and tissue distribution. These assessments are subjective and often show considerable variability. However, automated cancer diagnostic system based on three-dimensional image analysis based on nuclear bulging sign enables objective judgments using quantitative measurements. We expect that the shortage of pathologists will be improved when an automated cancer diagnosis system is developed.     

A feasibility study of virtual slides in surgical pathology in China

China's huge territorial expanse and its imbalance of regional economic development have resulted in an uneven distribution of experienced pathologists. Developing telepathology for consultation is of special relevance to China. We developed a newly designed telepathology workstation, which includes a small file size of each slide, permitting easy transmission, storage, and manipulation, and a feedback function, and also evaluated its feasibility in surgical pathology in China. Four hundred cases covering a broad spectrum of surgical pathology problems were investigated in a blinded fashion by the 2 pathologists using this virtual microscope system. These cases were then randomized and re-reviewed a second time with light microscope. Diagnoses and time spent for each diagnosis were recorded for both methods. The diagnostic accuracies achieved by viewing glass slides and virtual images were 97.25% (389 of 400) and 95.5% (382 of 400) for pathologist A and 96.25% (385 of 400) and 94.75% (379 of 400) for pathologist B, respectively. There was no significant diagnostic discrepancy between the 2 methods for the 2 pathologists. The average times for viewing a virtual slide were 3.41 and 5.24 minutes for pathologists A and B, respectively, whereas the average times for viewing a glass slide were 1.16 and 3.35 minutes for pathologists A and B. There was a statistical difference between the time costs of the 2 methods. However, the slight time increase using virtual slides is less than that using dynamic telepathology and traditional consultation, and is acceptable to the pathologists. These results showed that this newly designed virtual microscope system have an acceptable diagnostic accuracy that is of practical value and may be suitable for application in China.     

Evaluation of whole slide image immunohistochemistry interpretation in challenging prostate needle biopsies

Whole slide images (WSIs), also known as virtual slides, can support electronic distribution of immunohistochemistry (IHC) stains to pathologists that rely on remote sites for these services. This may lead to improvement in turnaround times, reduction of courier costs, fewer errors in slide distribution, and automated image analyses. Although this approach is practiced de facto today in some large laboratories, there are no clinical validation studies on this approach. Our retrospective study evaluated the interpretation of IHC stains performed in difficult prostate biopsies using WSIs. The study included 30 foci with IHC stains identified by the original pathologist as both difficult and pivotal to the final diagnosis. WSIs were created from the glass slides using a scanning robot (T2, Aperio Technologies, Vista, CA). An evaluation form was designed to capture data in 2 phases: (1) interpretation of WSIs and (2) interpretation of glass slides. Data included stain interpretations, diagnoses, and other parameters such as time required to diagnose and image/slide quality. Data were also collected from an expert prostate pathologist, consensus meetings, and a poststudy focus group. WSI diagnostic validity (intraobserver pairwise kappa statistics) was "almost perfect" for 1 pathologist, "substantial" for 3 pathologists, and "moderate" for 1 pathologist. Diagnostic agreement between the final/consensus diagnoses of the group and those of the domain expert was "almost perfect" (kappa = 0.817). Except for one instance, WSI technology was not felt to be the cause of disagreements. These results are encouraging and compare favorably with other efforts to quantify diagnostic variability in surgical pathology. With thorough training, careful validation of specific applications, and regular postsignout review of glass IHC slides (eg, quality assurance review), WSI technology can be used for IHC stain interpretation.     

An array microscope for ultrarapid virtual slide processing and telepathology. Design, fabrication, and validation study

This paper describes the design and fabrication of a novel array microscope for the first ultrarapid virtual slide processor (DMetrix DX-40 digital slide scanner). The array microscope optics consists of a stack of three 80-element 10 x 8-lenslet arrays, constituting a "lenslet array ensemble." The lenslet array ensemble is positioned over a glass slide. Uniquely shaped lenses in each of the lenslet arrays, arranged perpendicular to the glass slide constitute a single "miniaturized microscope." A high-pixel-density image sensor is attached to the top of the lenslet array ensemble. In operation, the lenslet array ensemble is transported by a motorized mechanism relative to the long axis of a glass slide. Each of the 80 miniaturized microscopes has a lateral field of view of 250 microns. The microscopes of each row of the array are offset from the microscopes in other rows. Scanning a glass slide with the array microscope produces seamless two-dimensional image data of the entire slide, that is, a virtual slide. The optical system has a numerical aperture of N.A.= 0.65, scans slides at a rate of 3 mm per second, and accrues up to 3,000 images per second from each of the 80 miniaturized microscopes. In the ultrarapid virtual slide processing cycle, the time for image acquisition takes 58 seconds for a 2.25 cm2 tissue section. An automatic slide loader enables the scanner to process up to 40 slides per hour without operator intervention. Slide scanning and image processing are done concurrently so that post-scan processing is eliminated. A virtual slide can be viewed over the Internet immediately after the scanning is complete. A validation study compared the diagnostic accuracy of pathologist case readers using array microscopy (with images viewed as virtual slides) and conventional light microscopy. Four senior pathologists diagnosed 30 breast surgical pathology cases each using both imaging modes, but on separate occasions. Of 120 case reads by array microscopy, there were 3 incorrect diagnoses, all of which were made on difficult cases with equivocal diagnoses by light microscopy. There was a strong correlation between array microscopy vs. "truth" diagnoses based on surgical pathology reports. The kappa statistic for the array microscopy vs. truth was 0.96, which is highly significant (z=10.33, p <0.001). There was no statistically significant difference between rates of agreement with truth between array microscopy and light microscopy (z=0.134, p >0.05). Array microscopy and light microscopy did not differ significantly with respect to the number/percent of correct decisions rendered (t=0.552, p=0.6376) or equivocal decisions rendered (t=2.449, p=0.0917). Pathologists rated 95.8% of array microscopy virtual slide images as good or excellent. None were rated as poor. The mean viewing time for a DMetrix virtual slide was 1.16 minutes. The DMetrix virtual slide processor has been found to reduce the virtual slide processing cycle more than 10 fold, as compared with other virtual slide systems reported to date. The virtual slide images are of high quality and suitable for diagnostic pathology, second opinions, expert opinions, clinical trials, education, and research.     

Eye-movement study and human performance using telepathology virtual slides: implications for medical education and differences with experience

A core skill in diagnostic pathology is light microscopy. Remarkably little is known about human factors that affect the proficiency of pathologists as light microscopists. The cognitive skills of pathologists have received relatively little attention in comparison with the large literature on human performance studies in radiology. One reason for this lack of formal visual search studies in pathology has been the physical restrictions imposed by the close positioning of a microscope operator's head to the microscope's eyepieces. This blocks access to the operator's eyes and precludes assessment of the microscopist's eye movements. Virtual slide microscopy now removes this barrier and opens the door for studies on human factors and visual search strategies in light microscopy. The aim of this study was to assess eye movements of medical students, pathology residents, and practicing pathologists examining virtual slides on a digital display monitor. Whole histopathology glass slide digital images, so-called virtual slides, of 20 consecutive breast core biopsy cases were used in a retrospective study. These high-quality virtual slides were produced with an array-microscope equipped DMetrix DX-40 ultrarapid virtual slide processor (DMetrix, Tucson, Ariz). Using an eye-tracking device, we demonstrated for the first time that when a virtual slide reader initially looks at a virtual slide his or her eyes are very quickly attracted to regions of interest (ROIs) within the slide and that these ROIs are likely to contain diagnostic information. In a matter of seconds, critical decisions are made on the selection of ROIs for further examination at higher magnification. We recorded: (1) the time virtual slide readers spent fixating on self-selected locations on the video monitor; (2) the characteristics of the ways the eyes jumped between fixation locations; and (3) x and y coordinates for each virtual slide marking the sites the virtual slide readers manually selected for zooming to higher ROI magnifications. We correlated the locations of the visually selected fixation locations and the manually selected ROIs. Viewing profiles were identified for each group. Fully trained pathologists spent significantly less time (mean, 4.471 seconds) scanning virtual slides when compared to pathology residents (mean, 7.148 seconds) or medical students (mean, 11.861 seconds), but had relatively prolonged saccadic eye movements (P < .0001). Saccadic eye movements are defined as eye movements between fixation locations. On the other hand, the pathologists spent significantly more time than trainees dwelling on the 3 locations they subsequently chose for zooming. Unlike either the medical students or the residents, the pathologists frequently choose areas for viewing at higher magnification outside of areas of foveal (central) vision. Eye movement studies of scanning pathways (scan paths) may be useful for developing eye movement profiles for individuals and for understanding the difference in performances between novices and experts. They may also be useful for developing new visual search strategies for rendering diagnoses on telepathology virtual slides.     

Web-based virtual microscopy in teaching and standardizing Gleason grading

Gleason grading forms the basis of prognostic and therapeutic assessment in prostatic carcinoma despite its subjective nature and substantial interobserver variation. The accuracy of Gleason grading can be improved by the use of educational tools such as reference images. However, conventional microscopy images are of limited educational value because it is neither possible to view the sample at different magnifications nor to navigate into different areas of the specimen. This limitation can be overcome by the use of virtual microscopy, which allows viewing entire digitized microscope slides. We created an interactive Web site ( www.webmicroscope.net/gleason ) featuring a comprehensive set of prostatic needle biopsies as virtual slides, which can be viewed with a standard Web browser (Internet Explorer or Netscape). To evaluate the validity of Web-based virtual microscopy for Gleason grading, an experienced uropathologist (TK) scored a series of 62 biopsies from the original glass slides and 6 weeks later from virtual slides on the Web site using an ordinary desktop computer. The intraobserver agreement was excellent, with identical Gleason scores found in 48 of the 62 cases ( kappa = 0.73). The 14 remaining scores differed only by 1 point on the Gleason scale (2-10). The virtual slides were viewed by 2 other uropathologists (PM and HH), with interobserver kappa coefficients ranging from 0.55 to 0.62, which is within the range of previously reported studies using glass slides. The 3 uropathologists' Gleason scores were included as reference scores on the Web site, which now serves as a publicly open platform for self-testing and learning of Gleason grading. We conclude that Web-based virtual microscopy is a promising new tool for teaching and standardizing Gleason grading.     

Interobserver and intraobserver reproducibility in digital and routine microscopic assessment of prostate needle biopsies

Advances in whole slide digital imaging in the past decade necessitate validation of these tools in each organ system in advance of clinical adoption. We assessed reproducibility in reporting prostate needle biopsy parameters among urologic pathologists using routine and digital microscopy in a consultation/second opinion-like setting. Four urologic pathologists evaluated a single core level from 50 diagnostically challenging needle biopsy specimens by routine microscopy and whole slide digital imaging. Interobserver and intraobserver agreement were calculated for primary and secondary Gleason grades, Gleason score, tumor quantitation (percentage and size in millimeters), and perineural invasion. Interobserver agreement for routine microscopy was excellent for primary Gleason grade (κ = 0.72) and good for all other parameters (κ ranging from 0.36 to 0.55). Whole slide digital imaging assessment yielded similar agreement for all parameters. Intraobserver agreement for primary Gleason grade and Gleason score was very good to excellent for all pathologists (all κ ≥ 0.65 and ≥ 0.73, respectively). Size of tumor in millimeters consistently displayed higher levels of agreement than percentage of tumor across media and pathologists. Digital assessment of routinely reported cancer parameters on prostatic needle biopsy for a given scanned core level is comparable to that of routine microscopy. These findings imply that histologic interpretation using dynamic whole slide images may accurately simulate routine microscopic evaluation in the consultation setting. Implementation of whole slide digital imaging in these scenarios may significantly reduce the workload of large referral centers in the near future and impact the manner in which pathologists seek second opinion consultation on challenging cases.     

Can histopathologists reliably diagnose molar pregnancy?

AIMS--To assess the degree of difficulty in diagnosing partial mole by analysing intraobserver and interobserver agreement among a group of pathologists for these diagnoses. METHODS--Fifty mixed cases of partial mole, complete mole, and non-molar pregnancy were submitted to seven histopathologists, two of whom are expert gynaecological pathologists; the other five were district general hospital consultants, one of whom works in Australia. These participants gave each slide a firm diagnosis of either partial mole, complete mole, or non-molar pregnancy. Some 12 months later, the slides were recorded and again submitted for a second diagnostic round to assess intraobserver as well as interobserver agreement. Standard histological criteria for each diagnostic category were circulated with the slides. RESULTS--kappa statistics showed that complete mole could be reliably distinguished from non-molar pregnancy, but neither non-molar pregnancy nor complete mole could be easily differentiated from partial mole. In only 35 out of 50 cases was there agreement between five or more of the seven participants. Agreement between the expert gynaecological pathologists was no better than for others in the group. Interestingly, the intraobserver agreement for each pathologist was good to excellent. CONCLUSIONS--These results imply that the reported histological criteria are either not being applied consistently or that they are lacking in practical use. An atypical growth pattern of trophoblast, rather than the polar accentuation seen in normal first trimester pregnancies, seems to be the important diagnostic histological feature for partial mole. Ploidy studies might also help with problem cases.     

Reproducibility in the diagnosis of needle core biopsies of non‐palpable breast lesions: an international study using virtual slides published on the world‐wide web

Zito F A, Verderio P, Simone G, Angione V, Apicella P, Bianchi S, Conde A F, Hameed O, Ibarra J, Leong A, Pennelli N, Pezzica E, Vezzosi V, Ventrella V, Pizzamiglio S, Paradiso A & Ellis I
(2010) Histopathology 56, 720–726
Reproducibility in the diagnosis of needle core biopsies of non‐palpable breast lesions: an international study using virtual slides published on the world‐wide web Aims: To conduct an internet‐based study using virtual slides (VS) of sterotactic core biopsy specimens of non‐palpable breast lesions in order to evaluate interobserver reproducibility between pathologists. Methods and results: A total of 18 breast lesions, determined to be histologically complex by two pathologists, were selected. Digitized VSs were then created using QuickTime Virtual Reality technology (Apple, Cupertino, CA, USA) and posted on the world‐wide web. In all, 10 pathologists completed the evaluations of 18 VSs using the five diagnostic categories (B1–B5) from the European guidelines for quality assurance in breast cancer screening and diagnosis. Their results were compared with those of every other participating pathologist, and were then individually compared with the results of a highly experienced breast pathologist (referee). Of the 18 cases, 10 (56%) were classified by the referee as borderline (B3 and B4). Comparisons with reference values showed a less than satisfactory level of reproducibility (median κ_w = 0.60). As regards interobserver reproducibility, results showed that, in general, the level of agreement was not satisfactory (median κ_w = 0.53). Conclusions: Overall, the findings are comparable to those quality control studies using circulating slides when analysis is done on borderline cases.     

Telecytology: Intraobserver and interobserver reproducibility in the diagnosis of cervical-vaginal smears

Telecytologic diagnosis of cervical-vaginal smears is potentially useful because it could allow more efficient use of cytopathologist resources and expertise. A pathologist in one location could, in principle, review cytotechnologists' findings using a video display hundreds or thousands of miles away. Currently, bandwidth restrictions limit practical implementation of such a system to review of fields that had been selected for review by the cytotechnologist. The purpose of our investigation was to evaluate how well this type of review correlates with a review in which the entire slide is available for examination by the pathologist. We prospectively selected 100 consecutive cervical-vaginal smears over an 11-day period in August 1999. For each smear, 4 to 12 fields containing abnormal cells from each slide were digitally imaged. Each of 3 pathologists reviewed all digitized images and all glass slides. Diagnoses based on selected digitized images were compared with those based on conventional pathologist review. The kappa statistic, a measure of chance-corrected agreement (reproducibility), was calculated in each setting. Overall, intraobserver and interobserver reproducibility of cervical-vaginal smear diagnoses is fair to excellent. The use of remote digital images for pathologist review did not introduce large (2-step) diagnostic disagreements. The disagreement between a pathologist's glass slide and digital diagnoses is less than that for different pathologists reviewing glass slides, although interobserver differences were even greater in the interpretation of digital images.     

Interobserver variability in the diagnosis of ulcerative colitis-associated dysplasia by telepathology.

Telepathology (TP) is the practice of remote diagnostic consultation of electronically transmitted, static, digitalized images. The diagnostic efficacy of TP-based consultation services has not been widely tested. Dysplasia that arises in association with chronic ulcerative colitis (CUC) is, at present, the most important marker of an increased risk of malignancy in patients with this disease. Unfortunately, dysplasia is difficult to diagnose histologically and, as a result, suffers from a significant degree of intra- and interobserver variability. Furthermore, it is often necessary to obtain expert consultation of potential CUC-associated dysplasia cases before treatment. Therefore, the aim of this study was to evaluate the utility and interobserver variability of diagnosing dysplasia in CUC with the use of TP. Static, electronically transmitted, digitalized images of 38 CUC cases with areas considered negative, indefinite, or positive for dysplasia (low or high grade) were evaluated independently by four gastrointestinal pathologists. All cases were then graded by each of the pathologists by light-microscopic examination of the hematoxylin and eosin-stained glass slides. The degree of interobserver variability was determined by kappa statistics. Overall, there was a fair degree of agreement (kappa = 0.4) among the four reviewing pathologists after analysis of the digitalized images. The poorest level of agreement was in the indefinite and low-grade dysplasia categories. Grouping together several diagnostic categories (for instance, indefinite and low-grade dysplasia, or low-grade dysplasia and high-grade dysplasia) had no effect on the overall level of agreement. The degree of variability in interpretation of glass slides was slightly better (kappa = 0.43) but still remained fair. After reviewing all cases by glass slide analysis, the diagnosis was changed in 38% of the slides; in the majority of these, the grade of dysplasia was increased. Use of TP for consultation in CUC-associated dysplasia has a moderate level of interobserver agreement. Because of a variety of technical reasons, diagnoses rendered by evaluation of digitalized images tended to be of a lower grade than that observed after a review of the glass slides.     

Validation of whole slide imaging for frozen section diagnosis of lymph node metastasis: A retrospective study from a tertiary care hospital in Thailand

BackgroundThe use of whole slide imaging (WSI) for frozen section (FS) diagnosis is helpful, particularly in the context of pathologist shortages. However, there is minimal data on such usage in resource-limited settings. This study aims to validate the use of WSI for FS diagnosis of lymph node metastasis using a low-cost virtual microscope scanner with consumer-grade laptops at a tertiary care hospital in Thailand.MethodsFS slides were retrieved for which the clinical query was to evaluate lymph node metastasis. They were digitized by a virtual microscope scanner (MoticEasyScan, Hong Kong) using up to 40× optical magnification. Three observers with different pathology experience levels diagnosed each slide, reviewing glass slides (GS) followed by digital slides (DS) after two weeks of a wash out period. WSI and GS diagnoses were compared. The time used for scanning and diagnosis of each slide was recorded.Results295 FS slides were retrieved and digitized. The first-time successful scanning rate was 93.6 %. The mean scanning time was 2 min per slide. Both intraobserver agreement and interobserver agreement of WSI and GS diagnoses were high (Cohen's K; kappa value >0.84). The time used for DS diagnosis decreased as the observer's experience with WSI increased.ConclusionsDespite varying pathological experiences, observers using WSI provided accurate FS diagnoses of lymph node metastasis. The time required for DS diagnoses decreased with additional observer's experience with WSI. Therefore, a WSI system containing low-cost scanners and consumer-grade laptops could be used for FS services in hospital laboratories lacking pathologists.     

Evaluation of the interobserver reproducibility of Gleason grading of prostatic adenocarcinoma using tissue microarrays

The Gleason system is the internationally recognized standard for grading prostate cancer, due mainly to its strong prognostic capability. However, interobserver reproducibility is variable in the community setting. Herein we present a novel approach to evaluating Gleason grading among pathologists using high-density tissue microarrays (TMAs). A CD-ROM containing 537 different TMA spot images of 0.6-mm diameter was sent to 10 genitourinary pathologists in France. The pathologists were expected to score each TMA spot based on their experience evaluating standard prostate biopsies, transurethral resections, and prostatectomy samples. There was no consensus meeting beforehand to agree on how the group would apply the Gleason grading system for this project. Percentage of agreement and kappa value were used to assess the level of agreement. A short questionnaire was sent to assess pathologists' opinion on this new approach to evaluating Gleason grading. An average of 311 images were analyzed (range, 104 to 537; median, 256.5). Four of the pathologists evaluated all 537 images and assigned Gleason grades to 149 images with an overall kappa for interobserver agreement for the exact score between 0.31 and 0.52 and between 0.45 to 0.69 if 3 Gleason categories (7) were used. When 2 categories were considered (7), kappa ranged from 0.58 to 0.83. All pathologists analyzed 104 images. Similar results were obtained with an agreement between 0.28 and 0.54 for the 3 Gleason categories. After finishing this test, 90% of genitourinary pathologists considered this approach useful for resident training and 90% for pathology teaching. We conclude that a Gleason score can be easily assigned to each TMA spot of a 0.6-mm-diameter prostate cancer sample. These data also indicated that using TMA spot images may be a good approach for teaching the Gleason grading system due to the small area of tissue.     

Evaluation of immunohistochemical staining using whole-slide imaging for HER2 scoring of breast cancer in comparison with real glass slides

Whole‐slide imaging (WSI) has been used for education and histological image preservation, and several studies have also reported its validity for practical pathological diagnosis. However, such studies employed materials stained with hematoxylin‐eosin (HE), and very few attempts have been made to use immunohistochemically stained materials for diagnostic purposes. In the present study, we investigated the availability of WSI diagnosis for immunohistochemically stained materials in place of routine glass slides. Thirty pathologists participated in a trial of HER2 expression diagnosis using WSI and compared the results with those obtained by light microscopy. The validity of WSI diagnosis (interobserver agreement) was rated as ‘substantial’ in comparison with glass slide diagnosis (κ‐value = 0.719). There was a tendency for observers to assign higher scores with WSI than with glass slides, probably because WSI requires slides to be scanned into a computer and observed via a monitor. Although we were able to demonstrate the potential utility of WSI for diagnosing immunostained materials, it must be borne in mind that there are some differences in visualization between WSI and glass slides.     

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

Puppa G, Senore C, Sheahan K, Vieth M, Lugli A, Zlobec I, Pecori S, Wang L M, Langner C, Mitomi H, Nakamura T, Watanabe M, Ueno H, Chasle J, Conley S A, Herlin P, Lauwers G Y & Risio M
(2012) Histopathology  61, 562–575 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. Conclusions: 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.     

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

Sanders D S A, Grabsch H, Harrison R, Bateman A, Going J, Goldin R, Mapstone N, Novelli M, Walker M M & Jankowski J
(2012) Histopathology  61, 795–800 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.     

Use of virtual microscopy for didactic live-audience presentation in anatomic pathology

Didactic presentations on the topic of anatomic pathology in front of a live audience have been largely dependent on the use of standard 2 x 2 inch projection slides (Kodachromes) of selected still images from the topic at hand. Because of the highly visual nature of the specialty of anatomic pathology, this method has had some serious limitations. With the advent of digital imaging techniques and the availability of new electronic software for the projection of images, new possibilities have become available for didactic presentations in anatomic pathology in front of a large, live audience. We describe a method whereby large digital images or "virtual slides" were produced from digitally scanned whole-mount sections of histologic glass slides and projected using a combination of PowerPoint (Microsoft Corp, Redmond, WA) and virtual microscopy in front of a live audience. To provide a seamless transition between the two presentation formats, the personal computer-based PowerPoint slides were hyperlinked to a browser-based virtual microscope viewer. The presenter, with the use of a mouse, was able to "move" the image of the scanned slide on the screen, to transition seamlessly among various magnifications, and to rapidly select from the whole-mount scanned slide among any areas of interest pertinent to the topic. Thus, the visual experience obtained by the audience simulated that of viewing a glass slide at a multi-headed microscope during a glass slide tutorial. Because this most closely approximates the experience of reviewing glass slides under the microscope for practicing pathologists, the educational experience of the presentation is greatly enhanced by the use of this technique. Also, this method permits making this type of presentation available to a much larger group of individuals in a live audience.     

Accuracy and reproducibility of telecytology diagnosis of cervical smears. A tool for quality assurance programs

We randomly selected 50 cervical smears (benign, 14; atypical squamous cells of undetermined significance [ASCUS], 5; low-grade squamous intraepithelial lesion [LSIL], 10; high-grade squamous intraepithelial lesion (HSIL), 12; squamous cell carcinoma, 6; adenocarcinoma, 3) and captured 1,181 digital images (518 MB) at a maximum resolution of 1,600 x 1,200 pixels and transmitted them by e-mail. Diagnosis of glass slides and digital images was done independently in a double-blind manner by 3 pathologists and 3 cytotechnologists, commencing with the diagnosis of digital images followed by diagnosis of glass slides 3 months later. The procedure was repeated after 3 months. Diagnoses were recorded as benign, ASCUS or atypical glandular cells of undetermined significance, LSIL, HSIL, squamous cell carcinoma or adenocarcinoma, and "inadequate for diagnosis." Diagnostic accuracy and interobserver reproducibility were analyzed using an intraclass correlation coefficient (ICC), which revealed good interobserver agreement for the first (0.72) and second (0.64) glass slide diagnoses and the first (0.72) and second (0.60) digital image diagnoses. The kappa values for intraobserver variation between first and second glass slide diagnoses and first and second digital image diagnoses showed moderate to excellent agreement. Digital images are suitable substitutes for glass slides; telecytology can be used as an alternative method for the cytologic diagnosis of cervical smears, particularly in quality assurance programs.     

Factors to keep in mind when introducing virtual microscopy

Digitization of glass slides and delivery of so-called virtual slides (VS) emulating a real microscope over the Internet have become reality due to recent improvements in technology. We have implemented a virtual microscope for instruction of medical students and for continuing medical education. Up to 30,000 images per slide are captured using a microscope with an automated stage. The images are post-processed and then served by a plain hypertext transfer protocol (http)-server. A virtual slide client (vMic) based on Macromedia's Flash MX, a highly accepted technology available on every modern Web browser, has been developed. All necessary virtual slide parameters are stored in an XML file together with the image. Evaluation of the courses by questionnaire indicated that most students and many but not all pathologists regard virtual slides as an adequate replacement for traditional slides. All our virtual slides are publicly accessible over the World Wide Web (WWW) at . Recently, several commercially available virtual slide acquisition systems (VSAS) have been developed that use various technologies to acquire and distribute virtual slides. These systems differ in speed, image quality, compatibility, viewer functionalities and price. This paper gives an overview of the factors to keep in mind when introducing virtual microscopy.Universal resource locators (URLs) visited at the time of writing (June 2005) may change or vanish with lapse of time. Therefore and because of usability, we have created a web page with all URLs that will be updated on a regular basis: .