|Year : 2015 | Volume
| Issue : 1 | Page : 1-3
The emerging world of digital pathology
Rajesh Singh Laishram
Department of Pathology, Regional Institute of Medical Sciences, Imphal, Manipur, India
|Date of Web Publication||17-Jun-2015|
Dr. Rajesh Singh Laishram
Department of Pathology, Regional Institute of Medical Sciences, Lamphelpat, Imphal - 795 004, Manipur
Source of Support: None, Conflict of Interest: None
Today, in the era of ever-growing advancement of technology, technology is no longer limited to smartphone or notebook. Information technology has started playing a crucial role even in the health care sector. The emerging technology is helping both software as well as hardware engineers to design lots of high-tech medical equipment, thereby helping medical professionals and even patients in several ways. Much transformation has occurred and evolved from telepathology to virtual microscopy, and now to a new dimension and concept called "digital pathology."
Keywords: Digital pathology, Telepathology, Virtual slides
|How to cite this article:|
Laishram RS. The emerging world of digital pathology. J Med Soc 2015;29:1-3
| Introduction|| |
The first concept of developing a functional robotic telepathology network with the aim of providing real-time expert opinions for frozen sections and difficult cases was put forth by Weinstein in the mid-1980s.  He is often cited as the father of telepathology. It was in 1990 that the first robotic microscope was maneuvered via the Internet by Weinstein.  Subsequently, in 1997, the first slide scanner was invented to measure preinvasive cancer by Bacus and his son Bacus Jr.  Soenksen, the founder of Aperio, imagined a world where the pathologist looked at computer monitors rather than microscopes.  These four inventors laid down the foundation for digital pathology.
Virtual microscopy then came to existence. It is the digital conversion of light microscopic slides in full resolution and their presentations over a computer network. In most cases, the slides were scanned with special instruments called slides scanners but these could also be produced by joining several photos taken through a microscope.
With the advent of virtual microscopy, diagnostic pathology is undergoing a digital revolution in the form of the so-called virtual slides. Virtual slides are enormous digital images produced by scanning glass slides at a very high resolution (200,000 dots per inch), resulting in images with sizes in gigapixels; these images are far larger than the images taken by even the best digital cameras.
The microscopic slides are fully and automatically digitalized with a 20 or 40 objective, and are saved in various formats depending on the different service providers. However, all the formats allow relatively fast visualization designed for this application (client/viewer) that is installed locally.
The concept of virtual microscopy then evolved into the concept of digital pathology.
Digital pathology can be stated as a powerful and dynamic image-based environment enabling the acquisition, management, and interpretation of pathology information generated from digitized glass slides. Digital pathology is enabled in part by virtual microscopy. Dirk Soenksen, the founder and Chief Executive Officer of the digital imaging company Aperio, stated that digital pathology was much more than just virtual microscopy. He stated that digital pathology appropriately defines the space we are in. It goes well beyond slide scanning. Virtual microscopy started with a box - a slide scanner that created virtual slides. But there are differences between the technical solution called virtual microscopy and this bigger space called digital microscopy.
Digital pathology versus traditional microscopy
Digital pathology can be considered as an adjunct to traditional microscopy. In traditional microscopy, we require a microscope to view the glass slide. We can only view one slide, one field of view, and one magnification at a time. If we want to do any sort of analysis with a microscope, we have to remember the information from each field of view. For example, if we want to compare two slides, we have to look at one slide, store the information in our brain bank, look at the slide, and try to remember the one we looked at before to make a comparison. In digital pathology, we have the benefit of doing things differently. We can view multiple digital slides on a computer monitor. We can pair them side-by-side if we want to count cells or quantify protein expression; these can be done easily by a computer program that can be seen on an image file called a digital slide. In case of traditional microscopy, if we want to share information with somebody in a distant place, the slide has to be mailed. But with digital pathology, we can share the information with anyone in the world immediately. It is also relatively easy to integrate a digital pathology system into a laboratory information system. Digital pathology can support the viewing and consolidation of disparate sources of information required for pathological purposes to do work more efficiently and productively.
Digital pathology environment
Digital pathology is much more than whole slide imaging (WSI); it has information security and creates an environment for managing data that comprises multi-gigabyte images that are incorporated. It also includes integration of the digital pathology information management system with autostainers, converslippers, and the laboratory management system. It comprises the following elements:
Conventional glass slides are converted to digital slides using a scanning device. Digital slide scanners are considered as successors of early telepathology systems that facilitated the transfer of static and dynamic images via computer networks for remote consultation and second opinion. 
Currently, there is a multitude of digital slide scanner manufacturers and models available in the market.  The choice of slide scanning equipment is a crucial step in the design of a fully digital pathology laboratory. Several important aspects such as the quality of the produced digital slides (image quality), available magnifications, number of focus planes, scanning speed, level of automation, and support of fluorescence imaging must be considered. 
Digital slides are accessible for viewing through a computer monitor and viewing software either locally or remotely via the Internet. Digital slides viewers can show an overview image, along with high-power view, enabling better orientation. Showing two or more slides side-by-side is a feature of many slide viewers, which can be useful for examining the same tissue stained with different stainings. Most slide viewers are offered as standalone applications by the scanner manufacturer, but cloud storage and viewing solutions are becoming more common.  Another interesting digital slide viewer implementation uses a combination of high resolution monitors and virtual reality technology to construct a digital pathology workstation that can perform as well as the conventional light microscope diagnosis.  The increased use of virtual slides in pathology laboratories has driven an interest in the development and use of automatic image analysis algorithms. The intended goal of these algorithms is to help pathologists with tasks that are notorious for their observer variability and/or are tedious and time-consuming. Some algorithms for the quantification of immunohistochemical stainings already have the approval of the USA Food and Drug Administration (FDA).  Current research in this field focuses on the development of methods for the analysis of hematoxylin- and eosin-stained slides, since this is the standard stain in every pathology laboratory. 
Digital slides are maintained in an information management system that allows archival and intelligent retrieval. Educational and research slides end up in the permanent storage where they are kept without an expiring time frame. Object-based storage offers complete redundancy of stored objects without the need to take incremental backups.  Most of the scanners in the market include one dimensional (1D) or two dimensional (2D) barcode scanners, which help in the integration with Laboratory Information Management System (LIMS). In this way, the image management system can store relevant metadata (e.g., the staining name) together with the image and the scan metadata. 
| Digital Pathology Workflow|| |
Currently, the typical workflow begins with the procedure performed on the patient, most commonly a biopsy or a resection. The material is then sent to a pathology department accompanied by an order (ideally in a digital way), along with relevant clinical information. This information usually comes out of the local electronic health records, together with localization and clinical data of the material. When the material is received in the pathology department, it is registered in the local laboratory information system before undergoing the necessary procedure in order to be processed to glass slides. Then, the glass slides are examined under a light microscope in order to produce the pathology report.  Switching the current workflow to a fully digital one would require glass slides to be scanned prior to sending them to pathologists, which can add cumulatively to the overall diagnosis time. This can be addressed by using faster scanners and integrating the scanning with the cover slipping and staining process. Thus, digital pathology workflow is integrated into the institution's overall operational environment.
Digital pathology systems offer pathologists an alternate, emerging mechanism to manage and interpret information. These offer increasingly fast and scalable hardware platforms for slide scanning and software that facilitates remote viewing, slide conferencing, archiving, and image analysis. Initially deployed and largely validated within the research and biopharmaceutical industries, digital pathology systems are being increasingly implemented for direct patient care. Improvements in image quality, scan time, and browsers will hopefully allow pathologists to switch to digital pathology more seamlessly, much like our radiology colleagues have done before us. Current progress on these and other issues, along with improving technology, will no doubt pave the way for increased adoption over the next decade, allowing the pathology community as a whole to harness the true potential of WSI for patient care. The digital decade will likely redefine how pathology is practiced and the role of the pathologist. 
Digital pathology's utility in the future
Many articles are being published regarding its use in routine pathologic diagnosis. , Validation of a WSI system for primary diagnosis in surgical pathology has been studied.  Even the concordance between digital pathology and light microscopy in general surgical pathology has been studied in a pilot study of 100 cases, and it was found that digital pathology is a safe and viable method of making a primary histological diagnosis. 
Digital pathology is being increasingly tried in the interpretation of immunohistochemistry (IHC) markers. Interpretation of human epidermal growth factor receptor 2 (HER2/neu) immunohistochemical expression with unaided as well as computer-aided digital microscopy as well has been documented. 
Digital pathology has penetrated classrooms, especially pathology teachings. It can effectively replace the traditional methods of learning pathology by providing mobility and convenience to medical students. 
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