Digital imaging in pathology: theoretical and practical considerations, and applications

A Practical Guide to Whole Slide Imaging: A White Paper From the Digital Pathology Association

Context.—

Whole slide imaging (WSI) represents a paradigm shift in pathology, serving as a necessary first step for a wide array of digital tools to enter the field. Its basic function is to digitize glass slides, but its impact on pathology workflows, reproducibility, dissemination of educational material, expansion of service to underprivileged areas, and intrainstitutional and interinstitutional collaboration exemplifies a significant innovative movement with far-reaching effects. Although the benefits of WSI to pathology practices, academic centers, and research institutions are many, the complexities of implementation remain an obstacle to widespread adoption. In the wake of the first regulatory clearance of WSI for primary diagnosis in the United States, some barriers to adoption have fallen. Nevertheless, implementation of WSI remains a difficult prospect for many institutions, especially those with stakeholders unfamiliar with the technologies necessary to implement a system or who cannot effectively communicate to executive leadership and sponsors the benefits of a technology that may lack clear and immediate reimbursement opportunity.

Objectives.—

To present an overview of WSI technology—present and future—and to demonstrate several immediate applications of WSI that support pathology practice, medical education, research, and collaboration.

Data Sources.—

Peer-reviewed literature was reviewed by pathologists, scientists, and technologists who have practical knowledge of and experience with WSI.

Conclusions.—

Implementation of WSI is a multifaceted and inherently multidisciplinary endeavor requiring contributions from pathologists, technologists, and executive leadership. Improved understanding of the current challenges to implementation, as well as the benefits and successes of the technology, can help prospective users identify the best path for success.

Updates in ophthalmic pathology

Ophthalmic pathology has a long history and rich heritage in the field of ophthalmology. This review article highlights updates in ophthalmic pathology that have developed significantly through the years because of the efforts of committed individuals and the confluence of technology such as molecular biology and digital pathology. This is an exciting period in the history of ocular pathology, with cutting-edge techniques paving the way for new developments in diagnostics, therapeutics, and research. Collaborations between ocular oncologists and pathologists allow for improved and comprehensive patient care. Ophthalmic pathology continues to be a relevant specialty that is important in the understanding and clinical management of ocular disease, education of eye care providers, and overall advancement of the field.

Medical Photography: Documentation, Art, and the Expression of Human Emotions

Medical photography is the state of the art for the documentation of dermatological disease. Experienced photographers take pictures of the most typical skin lesions in order to assist the clinician in assessing disease morphology and activity. In this study, we present 6 individuals with a variety of dermatoses and the expression of the patients’ emotions. The patients were asked to show their diseased skin and to present typically involved areas in the respective disease. The feelings expressed by their body movements and positions are viewed and interpreted. The patients’ history will be reported retrospectively. The aim of the report is to show that the art of medical photography does not only document skin lesions but also the disease burden and the associated impairment of quality of life. Moreover, dermatologic photography is a sensitive intervention for patients viewed in the light of teaching and patient care.

Modern Imaging Technologies in Toxicologic Pathology: An Overview

Modern imaging technology, now utilized in most biomedical research areas (bioimaging), enables the detection and visualization of biological processes at various levels of the molecule, organelle, cell, tissue, organ and/or whole body. In toxicologic pathology, the impact of modern imaging technology is becoming apparent from digital histopathology to novel molecular imaging for in vivo studies. This overview summarizes recent progresses in digital microscopy imaging and newly developed digital slide techniques. Applications of virtual microscopy imaging are discussed and compared to traditional optical microscopy reading. New generation digital pathology approaches, including automatic slide inspection, digital slide databases and image management are briefly introduced. Commonly used in vivo preclinical imaging technologies are also summarized. While most of these new imaging techniques are still undergoing rapid development, it is important that toxicologic pathologists embrace and utilize these technologies as advances occur.

Enhancing and Customizing Laboratory Information Systems to Improve/Enhance Pathologist Workflow

Optimizing pathologist workflow can be difficult because it is affected by many variables. Surgical pathologists must complete many tasks that culminate in a final pathology report. Several software systems can be used to enhance/improve pathologist workflow. These include voice recognition software, pre-sign-out quality assurance, image utilization, and computerized provider order entry. Recent changes in the diagnostic coding and the more prominent role of centralized electronic health records represent potential areas for increased ways to enhance/improve the workflow for surgical pathologists. Additional unforeseen changes to the pathologist workflow may accompany the introduction of whole-slide imaging technology to the routine diagnostic work.

Current status and future trends in telepathology and digital pathology

OBJECTIVE

The purpose of this study was to assess the current status and future trends in telepathology (TP) and digital pathology (DP) in central India.

MATERIALS AND METHODS

A self-constructed questionnaire including 12 questions was designed with five specialists, to improve the design ambiguity. The study was conducted through postal and online survey consisting of 12 questions and sent to 300 histopathologists.

RESULTS

A total of 247 histopathologists answered the survey. The overall response rate was 81%. 98% pathologists felt the need for TP and DP. 34% pathologists used digital photomicrographic images in routine practice. Utilization of DP in most efficient way was observed by 48% pathologists mainly for the purpose of teaching in academic institutions. 82% believed that TP is helpful to take an expert opinion whereas only26% believed that a second opinion has to be taken. With respect to limitations, 67% pathologists believed that its cost-effective whereas 51% revealed high use of TP in next 5 years.

CONCLUSIONS

Our survey shows that as the field evolves, pathologists are more towards welcoming TP and DP, provided frequent workshops and training programs are conducted. The results of this survey indicates that pathology staff across central India currently utilize gross digital images for educational or academic purposes. They also revealed that technology will be required in near future applications in academics, consultation and for medico-legal purposes.

Imaging and image management: A survey on current outlook and awareness in pathology practice

BACKGROUND

Flexibility of digital photography enables it to be an integral part of pathology practice. An assessment of guidelines of imaging is essential for proper usage of photographs.

OBJECTIVES

The purpose of the study was to assess awareness of oral pathologists about various aspects of medical photography.

METHODS

Questionnaire based on the availability of facilities, usage, technical details and ethical issues of medical photography was sent to postgraduate students and teaching faculties of Oral Pathology in various localities in India.

RESULTS

Photographs were taken mostly for the purposes of publication, medical documentation and education. Significant number of postgraduate students and faculties of Oral Pathology didn't receive any training or hadn't gone through any publications/books (P = 0.000) about medical photography. Consent for patient photography was taken by significant number of respondents (P = 0.000) but in a verbal form. Majority of people used image editing software, but 19.0% of faculties and 21.1% of postgraduate students were unaware of deleterious effect of image editing. Firm and sensible instructions concerning image storage, sharing and accessibility were not yet created.

CONCLUSION

This survey drew attention towards lack of proper understanding about the technical details, medical protocols and ethical issues related to medical photography. These findings recommend implementation of basic training for medical photography and policy for image management for students and faculties in every health care institution.

Digitized whole slides for breast pathology interpretation: current practices and perceptions

Digital whole slide imaging (WSI) is an emerging technology for pathology interpretation; however, little is known about pathologists' practice patterns or perceptions regarding WSI. A national sample (N = 252) of pathologists from New Hampshire, Vermont, Washington, Oregon, Arizona, Alaska, Maine, and Minnesota were surveyed in this cross-sectional study (2011-2013). The survey included questions on pathologists' experience, WSI practice patterns, and perceptions using a six-point Likert scale. Agreement was summarized with descriptive statistics to characterize pathologists' use and perceptions of WSI. The majority of participating pathologists were males (63%) between 40 and 59 years of age (70%) and not affiliated with an academic medical center (72%). Experience with WSI was reported by 49%. Types of use reported included CME/board exams/teaching (28%), tumor board/clinical conference (22%), archival purposes (6%), consultative diagnosis (4%), research (4%), and other uses (12%). Most respondents (79%) agreed that accurate diagnoses can be made with this technology, and that WSI is useful for obtaining a second opinion (88%). However, 78% of pathologists agreed that digital slides are too slow for routine clinical interpretation. Fifty-nine percent agreed that the benefits of WSI outweigh concerns. The respondents were equally split as to whether they would like to adopt WSI (51%) or not (49%). About half of pathologists reported experience with the WSI technology, largely for CME, licensure/board exams, and teaching. Positive perceptions regarding WSI slightly outweigh negative perceptions. Understanding practice patterns with WSI as dissemination advances may facilitate concordance of perceptions with adoption of the technology.

Enhancing and Customizing Laboratory Information Systems to Improve/Enhance Pathologist Workflow

Optimizing pathologist workflow can be difficult because it is affected by many variables. Surgical pathologists must complete many tasks that culminate in a final pathology report. Several software systems can be used to enhance/improve pathologist workflow. These include voice recognition software, pre-sign-out quality assurance, image utilization, and computerized provider order entry. Recent changes in the diagnostic coding and the more prominent role of centralized electronic health records represent potential areas for increased ways to enhance/improve the workflow for surgical pathologists. Additional unforeseen changes to the pathologist workflow may accompany the introduction of whole-slide imaging technology to the routine diagnostic work.

Current usage and future trends in gross digital photography in Canada

BACKGROUND

The purpose of this study was to assess the current usage, utilization and future direction of digital photography of gross surgical specimens in pathology laboratories across Canada.

METHODS

An online survey consisting of 23 multiple choice and free-text questions regarding gross digital photography was sent out to via email to laboratory staff across Canada involved in gross dissection of surgical specimens.

RESULTS

Sixty surveys were returned with representation from most of the provinces. Results showed that gross digital photography is utilized at most institutions (90.0%) and the primary users of the technology are Pathologists (88.0%), Pathologists' Assistants (54.0%) and Pathology residents (50.0%). Most respondents felt that there is a definite need for routine digital imaging of gross surgical specimens in their practice (80.0%). The top two applications for gross digital photography are for documentation of interesting/ complex cases (98.0%) and for teaching purposes (84.0%). The main limitations identified by the survey group are storage space (42.5%) and security issues (40.0%). Respondents indicated that future applications of gross digital photography mostly include teaching (96.6%), presentation at tumour boards/ clinical rounds (89.8%), medico-legal documentation (72.9%) and usage for consultation purposes (69.5%).

CONCLUSIONS

The results of this survey indicate that pathology staff across Canada currently utilizes gross digital images for regular documentation and educational reasons. They also show that the technology will be needed for future applications in teaching, consultation and medico-legal purposes.

Role of oestrogen receptors in bladder cancer development

Early studies documented the existence of sexual dimorphism in bladder cancer occurrence and progression, with a greater bladder cancer incidence in males than females. However, the progression of bladder cancer after diagnosis is much quicker in females than males. These findings can be explained by the effects of female hormones (predominantly oestrogens) and their binding receptors, including oestrogen receptor 1 (ESR1; also known as ERα), oestrogen receptor 2 (ESR2; also known as ERβ), and GPR30 protein on bladder cancer incidence and progression. Results from studies using various in vitro cell lines and in vivo mouse models demonstrate differential roles of oestrogen receptors in cancer initiation and progression. ERα suppresses bladder cancer initiation and invasion, whereas ERβ promotes bladder cancer initiation and progression. Mechanistic studies suggest that ERα and ERβ exert these effects via modulation of the AKT pathway and DNA replication complex, respectively. Targeting these signalling pathways--for example, with ERα agonists, ERβ antagonists, or selective oestrogen receptor modulators such as 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a]pyrimidin-3-yl]phenol (also known as PHTPP)--could lead to the development of new therapeutic approaches for controlling bladder cancer progression.

Guidelines for standard photography in gross and clinical anatomy

Photography has a widespread usage in medicine and anatomy. In this review, authors focused on the usage of photography in gross and clinical anatomy. Photography in gross and clinical anatomy is not only essential for accurate documentation of morphological findings but also important in sharing knowledge and experience. Photographs of cadavers are supposed to demonstrate the required information clearly. Thus, photographs should be taken with certain techniques in order to obtain high quality and standardization. Camera, lens, lighting, background, and certain photographic techniques are among the factors to achieve precise images. A set of suggested guidelines for accomplishing these standards are given for anatomists.

Shifting gears higher--digital slides in graduate education--4 years experience at Semmelweis University

Background

The spreading of whole slide imaging or digital slide systems in pathology as an innovative technique seems to be unstoppable. Successful introduction of digital slides in education has played a crucial role to reach this level of acceptance. Practically speaking there is no university institute where digital materials are not built into pathology education. At the 1st. Department of Pathology and Experimental Cancer Research, Semmelweis University optical microscopes have been replaced and for four years only digital slides have been used in education. The aim of this paper is to summarize our experiences gathered with the installation of a fully digitized histology lab for graduate education.

Methods

We have installed a digital histology lab with 40 PCs, two slide servers - one for internal use and one with external internet access. We have digitized hundreds of slides and after 4 years we use a set of 126 slides during the pathology course. A Student satisfaction questionnaire and a Tutor satisfaction questionnaire have been designed, both to be completed voluntarily to have feed back from the users. The page load statistics of the external slide server were evaluated.

Results

The digital histology lab served ~900 students and ~1600 hours of histology practice. The questionnaires revealed high satisfaction with digital slides. The results also emphasize the importance of the tutors' attitude towards digital microscopy as a factor influencing the students' satisfaction. The constantly growing number of page downloads from the external server confirms this satisfaction and the acceptance of digital slides.

Conclusions

We are confident, and have showed as well, that digital slides have got numerous advantages over optical slides and are more suitable in education.

Informatics for practicing anatomical pathologists: marking a new era in pathology practice

Informatics can be defined as using highly advanced technologies to improve patient diagnosis or management. Pathology informatics had evolved as a response to the overwhelming amount of information that was available, in an attempt to better use and maintain them. The most commonly used tools of informatics can be classified into digital imaging, telepathology, as well as Internet and electronic data mining. Digital imaging is the storage of anatomical pathology information, either gross pictures or microscopic slides, in an electronic format. These images can be used for education, archival, diagnosis, and consultation. Virtual microscopy is the more advanced form of digital imaging with enhanced efficiency and accessibility. Telepathology is now increasingly becoming a useful tool in anatomical pathology practice. Different types of telepathology communications are available for both diagnostic and consultation services. The spectrum of applications of informatics in the field of anatomical pathology is broad and encompasses medical education, clinical services, and pathology research. Informatics is now settling on solid ground as an important tool for pathology teaching, with digital teaching becoming the standard tool in many institutions. After a slow start, we now witness the transition of informatics from the research bench to bedside. As we are moving into a new era of extensive pathology informatics utilization, several challenges have to be addressed, including the cost of the new technology, legal issues, and resistance of pathologists. It is clear from the current evidence that pathology informatics will continue to grow and have a major role in the future of our specialty. However, it is also clear that it is not going to fully replace the human factor or the regular microscope.

Roundness variation in JPEG images affects the automated process of nuclear immunohistochemical quantification: correction with a linear regression model

The volume of digital image (DI) storage continues to be an important problem in computer-assisted pathology. DI compression enables the size of files to be reduced but with the disadvantage of loss of quality. Previous results indicated that the efficiency of computer-assisted quantification of immunohistochemically stained cell nuclei may be significantly reduced when compressed DIs are used. This study attempts to show, with respect to immunohistochemically stained nuclei, which morphometric parameters may be altered by the different levels of JPEG compression, and the implications of these alterations for automated nuclear counts, and further, develops a method for correcting this discrepancy in the nuclear count. For this purpose, 47 DIs from different tissues were captured in uncompressed TIFF format and converted to 1:3, 1:23 and 1:46 compression JPEG images. Sixty-five positive objects were selected from these images, and six morphological parameters were measured and compared for each object in TIFF images and those of the different compression levels using a set of previously developed and tested macros. Roundness proved to be the only morphological parameter that was significantly affected by image compression. Factors to correct the discrepancy in the roundness estimate were derived from linear regression models for each compression level, thereby eliminating the statistically significant differences between measurements in the equivalent images. These correction factors were incorporated in the automated macros, where they reduced the nuclear quantification differences arising from image compression. Our results demonstrate that it is possible to carry out unbiased automated immunohistochemical nuclear quantification in compressed DIs with a methodology that could be easily incorporated in different systems of digital image analysis.

Effects of image compression on automatic count of immunohistochemically stained nuclei in digital images

This study investigates the effects of digital image compression on automatic quantification of immunohistochemical nuclear markers. We examined 188 images with a previously validated computer-assisted analysis system. A first group was composed of 47 images captured in TIFF format, and other three contained the same images converted from TIFF to JPEG format with 3x, 23x and 46x compression. Counts of TIFF format images were compared with the other three groups. Overall, differences in the count of the images increased with the percentage of compression. Low-complexity images (< or =100 cells/field, without clusters or with small-area clusters) had small differences (<5 cells/field in 95-100% of cases) and high-complexity images showed substantial differences (<35-50 cells/field in 95-100% of cases). Compression does not compromise the accuracy of immunohistochemical nuclear marker counts obtained by computer-assisted analysis systems for digital images with low complexity and could be an efficient method for storing these images.

Quantification of diverse subcellular immunohistochemical markers with clinicobiological relevancies: validation of a new computer-assisted image analysis procedure

Tissue microarray technology and immunohistochemical techniques have become a routine and indispensable tool for current anatomical pathology diagnosis. However, manual quantification by eye is relatively slow and subjective, and the use of digital image analysis software to extract information of immunostained specimens is an area of ongoing research, especially when the immunohistochemical signals have different localization in the cells (nuclear, membrane, cytoplasm). To minimize critical aspects of manual quantitative data acquisition, we generated semi-automated image-processing steps for the quantification of individual stained cells with immunohistochemical staining of different subcellular location. The precision of these macros was evaluated in 196 digital colour images of different Hodgkin lymphoma biopsies stained for different nuclear (Ki67, p53), cytoplasmic (TIA-1, CD68) and membrane markers (CD4, CD8, CD56, HLA-Dr). Semi-automated counts were compared to those obtained manually by three separate observers. Paired t-tests demonstrated significant differences between intra- and inter-observer measurements, with more substantial variability when the cellular density of the digital images was > 100 positive cells/image. Overall, variability was more pronounced for intra-observer than for inter-observer comparisons, especially for cytoplasmic and membrane staining patterns (P < 0.0001 and P = 0.050). The comparison between the semi-automated and manual microscopic measurement methods indicates significantly lower variability in the results yielded by the former method. Our semi-automated computerized method eliminates the major causes of observer variability and may be considered a valid alternative to manual microscopic quantification for diagnostic, prognostic and therapeutic purposes.

Grid technology in tissue-based diagnosis: fundamentals and potential developments

Tissue-based diagnosis still remains the most reliable and specific diagnostic medical procedure. It is involved in all technological developments in medicine and biology and incorporates tools of quite different applications. These range from molecular genetics to image acquisition and recognition algorithms (for image analysis), or from tissue culture to electronic communication services. Grid technology seems to possess all features to efficiently target specific constellations of an individual patient in order to obtain a detailed and accurate diagnosis in providing all relevant information and references. Grid technology can be briefly explained by so-called nodes that are linked together and share certain communication rules in using open standards. The number of nodes can vary as well as their functionality, depending on the needs of a specific user at a given point in time. In the beginning of grid technology, the nodes were used as supercomputers in combining and enhancing the computation power. At present, at least five different Grid functions can be distinguished, that comprise 1) computation services, 2) data services, 3) application services, 4) information services, and 5) knowledge services. The general structures and functions of a Grid are described, and their potential implementation into virtual tissue-based diagnosis is analyzed. As a result Grid technology offers a new dimension to access distributed information and knowledge and to improving the quality in tissue-based diagnosis and therefore improving the medical quality.

Telepathy: maximizing resident exposure to surgical pathology decision making

BACKGROUND

General surgery residents are often not present for the critical intraoperative discussion between surgeon and pathologist regarding surgical pathology findings.

METHODS

A prospective pilot study analyzed general surgery resident exposure to surgical pathology. Thereafter, an operating room was equipped to view frozen section images in real time and verbally communicate with the pathologist (TelePATHy). Total operative cases, cases using frozen sections, and use of TelePATHy were recorded.

RESULTS

Most residents (78%) reported they were exposed to frozen-section surgical pathology < or =10% of the time. Overall, 202 operations were performed over the 123-day period. Forty-four cases had frozen-section specimens. General surgery residents were present for 40 cases. TelePATHy was successfully used in 32 cases (80%).

CONCLUSIONS

General surgery resident exposure to intraoperative pathology findings increased from a reported < or =10% to an observed 80%. TelePATHy is a novel intraoperative tool capable of maximizing the intraoperative experience of the surgical resident.

Strategies for laboratory cost containment and for pathologist shortage: centralised pathology laboratories with microwave- stimulated histoprocessing and telepathology

The imposition of laboratory cost containment, often from external forces, dictates the necessity to develop strategies to meet laboratory cost savings. In addition, the national and worldwide shortage of anatomical pathologists makes it imperative to examine our current practice and laboratory set-ups. Some of the strategies employed in other areas of pathology and laboratory medicine include improvements in staff productivity and the adoption of technological developments that reduce manual intervention. However, such opportunities in anatomical pathology are few and far between. Centralisation has been an effective approach in bringing economies of scale, the adoption of 'best practices' and the consolidation of pathologists, but this has not been possible in anatomical pathology because conventional histoprocessing takes a minimum of 14 hours and clinical turnaround time requirements necessitate that the laboratory and pathologist be in proximity and on site. While centralisation of laboratories for clinical chemistry, haematology and even microbiology has been successful in Australia and other countries, the essential requirements for anatomical pathology laboratories are different. In addition to efficient synchronised courier networks, a method of ultra-rapid tissue processing and some expedient system of returning the prepared tissue sections to the remote laboratory are essential to maintain the turnaround times mandatory for optimal clinical management. The advent of microwave-stimulated tissue processing that can be completed in 30-60 minutes and the immediate availability of compressed digital images of entire tissue sections via telepathology completes the final components of the equation necessary for making centralised anatomical pathology laboratories a reality.