Virtual 3D microscopy in pathology education

An efficient architecture to support digital pathology in standard medical imaging repositories

In the past decade, digital pathology and whole-slide imaging (WSI) have been gaining momentum with the proliferation of digital scanners from different manufacturers. The literature reports significant advantages associated with the adoption of digital images in pathology, namely, improvements in diagnostic accuracy and better support for telepathology. Moreover, it also offers new clinical and research applications. However, numerous barriers have been slowing the adoption of WSI, among which the most important are performance issues associated with storage and distribution of huge volumes of data, and lack of interoperability with other hospital information systems, most notably Picture Archive and Communications Systems (PACS) based on the DICOM standard. This article proposes an architecture of a Web Pathology PACS fully compliant with DICOM standard communications and data formats. The solution includes a PACS Archive responsible for storing whole-slide imaging data in DICOM WSI format and offers a communication interface based on the most recent DICOM Web services. The second component is a zero-footprint viewer that runs in any web-browser. It consumes data using the PACS archive standard web services. Moreover, it features a tiling engine especially suited to deal with the WSI image pyramids. These components were designed with special focus on efficiency and usability. The performance of our system was assessed through a comparative analysis of the state-of-the-art solutions. The results demonstrate that it is possible to have a very competitive solution based on standard workflows.

Cytopathology whole slide images and adaptive tutorials for postgraduate pathology trainees: a randomized crossover trial

To determine whether cytopathology whole slide images and virtual microscopy adaptive tutorials aid learning by postgraduate trainees, we designed a randomized crossover trial to evaluate the quantitative and qualitative impact of whole slide images and virtual microscopy adaptive tutorials compared with traditional glass slide and textbook methods of learning cytopathology. Forty-three anatomical pathology registrars were recruited from Australia, New Zealand, and Malaysia. Online assessments were used to determine efficacy, whereas user experience and perceptions of efficiency were evaluated using online Likert scales and open-ended questions. Outcomes of online assessments indicated that, with respect to performance, learning with whole slide images and virtual microscopy adaptive tutorials was equivalent to using traditional methods. High-impact learning, efficiency, and equity of learning from virtual microscopy adaptive tutorials were strong themes identified in open-ended responses. Participants raised concern about the lack of z-axis capability in the cytopathology whole slide images, suggesting that delivery of z-stacked whole slide images online may be important for future educational development. In this trial, learning cytopathology with whole slide images and virtual microscopy adaptive tutorials was found to be as effective as and perceived as more efficient than learning from glass slides and textbooks. The use of whole slide images and virtual microscopy adaptive tutorials has the potential to provide equitable access to effective learning from teaching material of consistently high quality. It also has broader implications for continuing professional development and maintenance of competence and quality assurance in specialist practice.

Application of whole slide image markup and annotation for pathologist knowledge capture

Objective:

The ability to transfer image markup and annotation data from one scanned image of a slide to a newly acquired image of the same slide within a single vendor platform was investigated. The goal was to study the ability to use image markup and annotation data files as a mechanism to capture and retain pathologist knowledge without retaining the entire whole slide image (WSI) file.

Methods:

Accepted mathematical principles were investigated as a method to overcome variations in scans of the same glass slide and to accurately associate image markup and annotation data across different WSI of the same glass slide. Trilateration was used to link fixed points within the image and slide to the placement of markups and annotations of the image in a metadata file.

Results:

Variation in markup and annotation placement between WSI of the same glass slide was reduced from over 80 μ to less than 4 μ in the x-axis and from 17 μ to 6 μ in the y-axis (P < 0.025).

Conclusion:

This methodology allows for the creation of a highly reproducible image library of histopathology images and interpretations for educational and research use.

Virtual dermatohistopathology at http://www.pathowiki.org

PATHOWIKI (http://www.pathowiki.org) is a new specialized information system in the form of a web-based wiki with content from all sub-disciplines of human pathology. Essential components are articles and specimens which are located thematically in dermatopathology. The project is presented on the basis of impressive examples and possibilities. The ability to link all kinds of content and integrate pattern analysis theories creates an effective tool for teaching and training in dermatopathology. Collaborative work ensures the effective usage of available resources and a continually growing amount of content, the quality of which depends on the number of users and should be as high as possible. Therefore, all interested colleagues are invited to support the project.

[Pathowiki. A free expert database for pathology]

The project Pathowiki (www.pathowiki.org) is a free expert database for texts, images, virtual slides and links to all subject areas of pathology in the internet. The aim of this project is to integrate all available information and media, in particular virtual microscopy, to achieve a fast overview of a relevant subject area. Here we present the project’s basic functions and applications and evaluate the project with respect to the ongoing digital developments in pathology.

Telecytology: Clinical applications, current challenges, and future benefits

Telecytology is the interpretation of cytology material at a distance using digital images. For more than a decade, pioneering efforts to introduce telecytology into clinical practice have been reported. A Medline search for "telecytology" and "cytology" reveals a voluminous literature, though much of what has been published to date is based on technologies that are rapidly becoming obsolete. The technological limitations of previous techniques, including the transmission of static digital images and dynamic streaming images, have limited telecytology to minor niches. The primary problem with these technologies is that the remote viewer can only see a small fraction of the material on the original slides, introducing the possibility of diagnostic error based not only on image quality but also on image selection. Remote robotic microscopy offers one possible solution to this problem, but to date has found limited acceptance, principally attributable to slow operating times. Whole slide imaging seems to be a much more promising solution, though cytology-specific literature regarding its use is still scant. The advent of whole slide imaging opens up new possibilities for telecytology by enabling high-quality images of entire cytology specimens to be available to anyone, anywhere via the Internet. Although challenges remain, especially with regard to capturing the full microscopy experience including multiple planes of focus and sharp high-powered images, rapidly advancing technology promises to overcome these limitations. Increasing application of whole slide imaging technology in surgical pathology will undoubtedly also increase its application to cytology due to the increasing affordability and practicality of the equipment as it serves a larger number of useful roles within a pathology department. The current and expanding applications of telecytology for clinical practice, education, quality assurance, and testing will be reviewed.

Lossless compression of JPEG2000 whole slide images is not required for diagnostic virtual microscopy

The use of lossy compression in medical imaging is controversial, although it is inevitable to reduce large data amounts. In contrast with lossy compression, lossless compression does not impair image quality. In addition to our previous studies, we evaluated virtual 3-dimensional microscopy using JPEG2000 whole slide images of gastric biopsy specimens with or without Helicobacter pylori gastritis using lossless compression (1:1) or lossy compression with different compression levels: 5:1, 10:1, and 20:1. The virtual slides were diagnosed in a blinded manner by 3 pathologists using the updated Sydney classification. The results showed no significant differences in the diagnosis of H pylori between the different levels of compression in virtual microscopy. We assume that lossless compression is not required for diagnostic virtual microscopy. The limits of lossy compression in virtual microscopy without a loss of diagnostic quality still need to be determined. Analogous to the processes in radiology, recommendations for the use of lossy compression in diagnostic virtual microscopy have to be worked out by pathology societies.

Digital imaging in cytopathology

Rapid advances are occurring in the field of cytopathology, particularly in the field of digital imaging. Today, digital images are used in a variety of settings including education (E-education), as a substitute to multiheaded sessions, multisite conferences, publications, cytopathology web pages, cytology proficiency testing, telecytology, consultation through telecytology, and automated screening of Pap test slides. The accessibility provided by digital imaging in cytopathology can improve the quality and efficiency of cytopathology services, primarily by getting the expert cytopathologist to remotely look at the slide. This improved accessibility saves time and alleviates the need to ship slides, wait for glass slides, or transport pathologists. Whole slide imaging (WSI) is a digital imaging modality that uses computerized technology to scan and convert pathology and cytology glass slides into digital images (digital slides) that can be viewed remotely on a workstation using viewing software. In spite of the many advances, challenges remain such as the expensive initial set-up costs, workflow interruption, length of time to scan whole slides, large storage size for WSI, bandwidth restrictions, undefined legal implications, professional reluctance, and lack of standardization in the imaging process.

Z-axis video for cytology database is a useful tool for the case presentation prior to the cytology training workshop

We have built a database on the Internet managing z-axis video for cytology (Zavic), and report on a new style of case discussion supported by the Zavic database. Z-axis video for cytology is a movie file derived from the video recording of a microscopic field with changes in the focus. We used it for the case presentation of EUS-FNA of pancreatic lesions on the Internet prior to a training workshop. The attendees were asked to observe the Zavic and to make diagnoses of 20 cases before the workshop. Fourteen attendees also observed lesions under a microscope on that day, and the results were compared with those of Zavic observation. The evaluation of the Zavic database (DB) was surveyed by a questionnaire. The average number of accurate diagnoses by 46 Zavic observers was 10.8. These accuracies for those who observed both the Zavic and glass slides were 11.57 and 11.43, respectively, for the videos and slides. Compared with Zavic observation alone, the diagnoses with glass slide observation were shifted to a correct diagnosis in two cases, but were shifted to an incorrect diagnosis in two cases. Approximately 60% of Zavic observers replied in the questionnaire that the movies on Zavic DB started to play within 3-4 seconds after clicking the play button. We successfully carried out the new style of case discussion supported by the Zavic DB. It was evaluated favorably by many attendees, who were psychologically still dependent on the glass slide observation.