Digital image acquisition using a consumer-type digital camera in the anatomic pathology setting

Imaging is central to anatomic pathology. The captured images are used for documentation, archiving, teaching, and publication. The advent of low-cost, consumer-type, high-end digital cameras has provided a convenient, easy-to-use alternative for routine image acquisition. The various applications for digital image acquisition in anatomic pathology include, among others, digitizing conventional photographs, digital gross photography and digital macrophotography, digitizing radiographic images, and digital photomicrography. This article reviews digital image acquisition in the anatomic pathology setting using a consumer-type digital camera. The camera type chosen as an example for the discussion was selected for its popularity and wide use among pathologists and for its potential to function as a sole image input device in all applications combined. Techniques and accessories to further increase the functionality of the camera and help overcome some of the commonly encountered problems in some applications are described.     

Digital pathology: current status and future perspectives

During the last decade pathology has benefited from the rapid progress of image digitizing technology. The improvement in this technology had led to the creation of slide scanners which are able to produce whole slide images (WSI) which can be explored by image viewers in a way comparable to the conventional microscope. The file size of the WSI ranges from a few megabytes to several gigabytes, leading to challenges in the area of image storage and management when they will be used routinely in daily clinical practice. Digital slides are used in pathology for education, diagnostic purposes (clinicopathological meetings, consultations, revisions, slide panels and, increasingly, for upfront clinical diagnostics) and archiving. As an alternative to conventional slides, WSI are generally well accepted, especially in education, where they are available to a large number of students with the full possibilities of annotations without the problem of variation between serial sections. Image processing techniques can also be applied to WSI, providing pathologists with tools assisting in the diagnosis-making process. This paper will highlight the current status of digital pathology applications and its impact on the field of pathology.     

Digital imaging guidelines for pathology: a proposal for general and academic use

Digital imaging is an inexpensive and widely available tool that is used by most pathologists in patient reports, education, publication, diagnosis, and data archival. Its popularity is due, in part, to the ease of modifying, storing, enhancing, and annotating images. Since digital manipulation is essentially undetectable in the final product, it poses the potential risk for fraudulent manipulation and heightens the possibility of unintentional misrepresentation. In an attempt to ensure a high degree of uniformity and quality, and to create a professional standardization amongst pathologists, digital imaging guidelines are proposed for use in general and academic practice.     

Digital Pathology Consultations—a New Era in Digital Imaging, Challenges and Practical Applications

Digital pathology has grown dramatically in the last 10 years and has created opportunities to not only support the triaging of difficult cases among specialists within an organization, but also enable remote pathology consultations with external organizations across the world. This study investigated one organization's need for a vendor agnostic Digital Pathology Consultation workflow solution that overcomes the challenges associated with the transfer of large studies across a local area network or across the Internet. The organization investigated is a large multifacility healthcare organization that consists of 20 hospitals spread across a wide geographical area. The organization has one of the largest academic pathology departments in the USA, with more than 100 diagnostic anatomic pathologists. This organization developed a set of web-based tools to support the workflow of digital pathology consultations and allow the viewing of whole slide images. The challenges and practical implementations of two different use cases are addressed: the occasional end user (professional or patient) requesting a second opinion and the external laboratory or hospital looking for an established consultative relationship with a large volume of cases. The solution presented in this study addresses the challenges associated with the distribution of large images and the lack of established imaging standards, while providing for a convenient and secure portal for pathologist report entry and distribution.     

Digital image capture applied to electron microscopic examination of renal biopsies

AIMS: Digital image capture systems to replace traditional film cameras are now available for most electron microscopes. For a diagnostic electron microscope laboratory the test of this new technology is in its application to the examination of renal biopsy specimens. METHODS: A long-term comparison is made between the work procedures employed with conventional film photography versus digital image capture in routine renal biopsy examination. RESULTS: Digital image capture has lead to a reduction in turnaround time and allows for more images to be collected per case, providing more diagnostic information. Ultrastructural measurement is made easier, accuracy of patient records is improved and electronic communication of results is more accessible. Significant operational cost savings are also possible. CONCLUSION: A quicker and more comprehensive assessment of renal biopsy specimens is possible using digital image capture for ultrastructural examination.     

The future of telepathology for the developing world

Physician shortages are acute in developing countries, where disease burden is the greatest and resources for health care are very limited. A lack of pathologists in these countries has lead to delays in diagnosis and misdiagnoses that adversely affect patient care and survival. The introduction of telepathology into countries with limited resources for health care is but one of multiple approaches that can be used to alleviate the problem. Telepathology is the electronic transmission of digital images that can be used for education and diagnostic consultation. A basic system consists of a microscope with a mounted digital camera linked to a computer. The ability to produce histologic slides, to repair and maintain equipment, and to provide training are also needed for the successful use of this technology. iPath is a Web-based, open platform, software application which was developed at the University of Basel, Switzerland, for telepathology and which brings together pathologists from around the world to provide telepathology support for diagnostic consultation and provides education to centers with limited resources. The use of virtual-slide technology to provide a digital image of an entire glass slide is another technology for diagnostic consultation and pathology education. This technology requires more costly resources to support it, which may limit its utility in many areas. Telepathology can generate collections of digital images and virtual slides needed for training indigenous pathologists in their countries to become self-sufficient. Thus, the long-term goal of this technology is to improve patient care and survival.     

How to improve microscopic images obtained with consumer-type digital cameras

AIM: Digital imaging is useful in conventional photography because it immediately provides images, and the image quality can be improved afterwards by the use of computer programs. The major disadvantages of consumer-type digital cameras mounted on microscopes are (i) unequal illumination through the image, and (ii) a coloured background. A computer program was specifically adapted and refined to improve images obtained with consumer-type digital cameras mounted on microscopes. METHODS AND RESULTS: An approach using a division operation between the specimen image and a background image leads to homogeneous illumination throughout the image, with automatically corrected brightness and white background. The correct colour spectrum is preserved by correction of the histogram. This approach was obtained from the freeware computer program 'Image Arithmetic'. In a test, three different consumer-type digital cameras (Sony, Nikon, Olympus) on different microscopes were used to obtain images of different types of histological specimens (cervical smear, bone marrow biopsy, and colonic biopsy). The computer program dramatically improved the quality of images obtained with all tested cameras. CONCLUSION: Using this approach, even low-cost digital cameras mounted on microscopes produce brilliant images with homogeneous illumination and a white background, the image quality being comparable with expensive cameras especially designed for microscopes.     

Concordance between whole-slide imaging and light microscopy for routine surgical pathology

The use of high-resolution digital images of histopathology slides as a routine diagnostic tool for surgical pathology was investigated. The study purpose was to determine the diagnostic concordance between pathologic interpretations using whole-slide imaging and standard light microscopy. Two hundred fifty-one consecutive surgical pathology cases (312 parts, 1085 slides) from a single pathology service were included in the study after cases had been signed out and reports generated. A broad array of diagnostic challenges and tissue sources were represented, including 52 neoplastic cases. All cases were digitized at ×20 and presented to 2 pathologists for diagnosis using whole-slide imaging as the sole diagnostic tool. Diagnoses rendered by the whole-slide imaging pathologists were compared with the original light microscopy diagnoses. Overall concordance between whole-slide imaging and light microscopy as determined by a third pathologist and jury panel was 96.5% (95% confidence interval, 94.8%-98.3%). Concordance between whole-slide imaging pathologists was 97.7% (95% confidence interval, 94.7%-99.2%). Five cases were discordant between the whole-slide imaging diagnosis and the original light microscopy diagnosis, of which 2 were clinically significant. Discordance resulted from interpretive criteria or diagnostic error. The whole-slide imaging modality did not contribute to diagnostic differences. Problems encountered by the whole-slide imaging pathologists primarily involved the inability to clearly visualize nuclear detail or microscopic organisms. Technical difficulties associated with image scanning required at least 1 slide be rescanned in 13% of the cases. Technical and operational issues associated with whole-slide imaging scanning devices used in this study were found to be the most significant obstacle to the use of whole-slide imaging in general surgical pathology.     

Automated image analysis of digital colposcopy for the detection of cervical neoplasia

Digital colposcopy is a promising technology for the detection of cervical intraepithelial neoplasia. Automated analysis of colposcopic images could provide an inexpensive alternative to existing screening tools. Our goal is to develop a diagnostic tool that can automatically identify neoplastic tissue from digital images. A multispectral digital colposcope (MDC) is used to acquire reflectance images of the cervix with white light before and after acetic-acid application in 29 patients. A diagnostic image analysis tool is developed to identify neoplasia in the digital images. The digital image analysis is performed in two steps. First, similar optical patterns are clustered together. Second, classification algorithms are used to determine the probability that these regions contain neoplastic tissue. The classification results of each patient's images are assessed relative to the gold standard of histopathology. Acetic acid induces changes in the intensity of reflected light as well as the ratio of green to red reflected light. These changes are used to differentiate high-grade squamous intraepithelial (HGSIL) and cancerous lesions from normal or low-grade squamous intraepithelial (LGSIL) tissue. We report diagnostic performance with a sensitivity of 79% and a specificity of 88%. We show that diagnostically useful digital images of the cervix can be obtained using a simple and inexpensive device, and that automated image analysis algorithms show a potential to identify histologically neoplastic tissue areas.     

Assessment of parathyroid gland cellularity by digital slide analysis

BackgroundComputer-aided examination of digital tissue images has attracted attention in recent years. Application in the field of parathyroid pathology has not been studied previously. It holds a potential to assist in the examination of parathyroid gland adenoma or hyperplasia.ObjectivesTo explore parathyroid cell detection of slide images by digital tissue analysis and compare the results to standard human processing.Methods47 incisional biopsies of healthy appearing parathyroid glands were evaluated for their cellularity level. First, by the standard examination using microscopy by three independent pathologists. We compared the mean cellularity grading of the pathologists to the output of a computerized cell detection software.ResultsA disagreement was found between the standard human cellularity grading and the digital analysis output. However, the digital analysis reaches a 94% specificity and 48% sensitivity to predict high cellularity (>60% parenchymal cells).ConclusionsDigital analysis of parathyroid tissue can be used as a tool for hypercellularity elimination, therefore assisting in the diagnosis of parathyroid cell hyperplasia. Additional studies using more advanced algorithms are necessary for further precision enhancement.     

Digital imaging applications in anatomic pathology

Digital imaging has progressed at a rapid rate and is likely to eventually replace chemical photography in most areas of professional and amateur digital image acquisition. In pathology, digital microscopy has implications beyond that of taking a photograph. The arguments for adopting this new medium are compelling, and given similar developments in other areas of pathology and radiologic imaging, acceptance of the digital medium should be viewed as a component of the technological evolution of the laboratory. A digital image may be stored, replicated, catalogued, employed for educational purposes, transmitted for further interpretation (telepathology), analyzed for salient features (medical vision/image analysis), or form part of a wider digital healthcare strategy. Despite advances in digital camera technology, good image acquisition still requires good microscope optics and the correct calibration of all system components, something which many neglect. The future of digital imaging in pathology is very promising and new applications in the fields of automated quantification and interpretation are likely to have profound long-term influence on the practice of anatomic pathology. This paper discusses the state of the art of digital imaging in anatomic pathology.     

Digital pathology and artificial intelligence as the next chapter in diagnostic hematopathology

Digital pathology has a crucial role in diagnostic pathology and is increasingly a technological requirement in the field. Integration of digital slides into the pathology workflow, advanced algorithms, and computer-aided diagnostic techniques extend the frontiers of the pathologist's view beyond the microscopic slide and enable true integration of knowledge and expertise. There is clear potential for artificial intelligence (AI) breakthroughs in pathology and hematopathology.In this review article, we discuss the approach of using machine learning in the diagnosis, classification, and treatment guidelines of hematolymphoid disease, as well as recent progress of artificial intelligence in flow cytometric analysis of hematolymphoid diseases. We review these topics specifically through the potential clinical applications of CellaVision, an automated digital image analyzer of peripheral blood, and Morphogo, a novel artificial intelligence-based bone marrow analyzing system. Adoption of these new technologies will allow pathologists to streamline workflow and achieve faster turnaround time in diagnosing hematological disease.     

Accuracy is in the eyes of the pathologist: The visual interpretive process and diagnostic accuracy with digital whole slide images

Digital whole slide imaging is an increasingly common medium in pathology, with application to education, telemedicine, and rendering second opinions. It has also made it possible to use eye tracking devices to explore the dynamic visual inspection and interpretation of histopathological features of tissue while pathologists review cases. Using whole slide images, the present study examined how a pathologist’s diagnosis is influenced by fixed case-level factors, their prior clinical experience, and their patterns of visual inspection. Participating pathologists interpreted one of two test sets, each containing 12 digital whole slide images of breast biopsy specimens. Cases represented four diagnostic categories as determined via expert consensus: benign without atypia, atypia, ductal carcinoma in situ (DCIS), and invasive cancer. Each case included one or more regions of interest (ROIs) previously determined as of critical diagnostic importance. During pathologist interpretation we tracked eye movements, viewer tool behavior (zooming, panning), and interpretation time. Models were built using logistic and linear regression with generalized estimating equations, testing whether variables at the level of the pathologists, cases, and visual interpretive behavior would independently and/or interactively predict diagnostic accuracy and efficiency. Diagnostic accuracy varied as a function of case consensus diagnosis, replicating earlier research. As would be expected, benign cases tended to elicit false positives, and atypia, DCIS, and invasive cases tended to elicit false negatives. Pathologist experience levels, case consensus diagnosis, case difficulty, eye fixation durations, and the extent to which pathologists’ eyes fixated within versus outside of diagnostic ROIs, all independently or interactively predicted diagnostic accuracy. Higher zooming behavior predicted a tendency to over-interpret benign and atypia cases, but not DCIS cases. Efficiency was not predicted by pathologist- or visual search-level variables. Results provide new insights into the medical interpretive process and demonstrate the complex interactions between pathologists and cases that guide diagnostic decision-making. Implications for training, clinical practice, and computer-aided decision aids are considered.     

Diagnostic accuracy of second-opinion diagnoses based on still images

Second opinion of histological specimens is an important part of the daily routine in anatomic pathology practices. Today, extramural second opinion can be easily obtained by sending still images via an electronic network. The aim of this study was to examine the diagnostic accuracy of second opinion diagnosis based on still images selected from glass slides of 90 archived cases originally referred for extramural second opinion. Two pathologists together diagnosed first the still images (phase 1) and then the glass slides (phase 2). Phase 1 and phase 2 diagnoses were compared with the original second opinion diagnoses (OSODs). The pathologists achieved the same diagnostic results in phase 1 and in phase 2 measured against the OSOD, 67.8% (n = 61) and 68.9% (n = 62) complete agreement, respectively. In 29 cases in phase 1, the diagnoses were discordant with the OSOD. Three cases had incorrect benign diagnoses and 8 cases had incorrect malignant diagnoses. There were 8 false-negative diagnoses regarding malignancy, 6 false-positive diagnoses regarding malignancy, and 4 other discordant diagnoses. Eleven of the 29 discordant diagnoses could have had clinical implications. In interpreting these results, it is important to acknowledge the observer variability in diagnostic histopathology in general. In conclusion, the results support the concept of using still images to obtain second opinion diagnosis.     

Cost-effective handling of digital medical images in the telemedicine environment

BACKGROUND: This paper concentrates on strategies for less costly handling of medical images. Aspects of digitization using conventional digital cameras, lossy compression with good diagnostic quality, and visualization through less costly monitors are discussed. METHOD: For digitization of film-based media, subjective evaluation of the suitability of digital cameras as an alternative to the digitizer was undertaken. To save on storage, bandwidth and transmission time, the acceptable degree of compression with diagnostically no loss of important data was studied through randomized double-blind tests of the subjective image quality when compression noise was kept lower than the inherent noise. A diagnostic experiment was undertaken to evaluate normal low cost computer monitors as viable viewing displays for clinicians. RESULTS: The results show that conventional digital camera images of X-ray images were diagnostically similar to the expensive digitizer. Lossy compression, when used moderately with the imaging noise to compression noise ratio (ICR) greater than four, can bring about image improvement with better diagnostic quality than the original image. Statistical analysis shows that there is no diagnostic difference between expensive high quality monitors and conventional computer monitors. CONCLUSION: The results presented show good potential in implementing the proposed strategies to promote widespread cost-effective telemedicine and digital medical environments.     

A practical application of quantitative vascular image analysis in breast pathology

Aims

Quantitative image analysis of histopathology slides is becoming an important technology in diagnostic pathology. To this end, it is essential to combine a robust image analysis software with the most commonly used immunohistochemical staining methods. In this investigation, we describe a practical application of NIH ImageJ software for quantitative vascular image analysis for diaminobenzene chromogen-based CD34 immunostain in breast cancer. CD34 immunostain is in a unique position to identify lymphangiogenesis and angiogenesis simultaneously in a given tumor tissue. This investigation aims at establishing a practical quantitative vascular image analysis solution for diagnostic pathologists by using ImageJ, and CD34 immunostain.

Methods and results

Tissue microarray slides containing breast cancer tissue were immunostained for CD34 for simultaneous identification of lymphatic endothelial cells (LEC) and blood vessel endothelial cells (BEC). Digital images were analyzed using NIH ImageJ software. A CD34 score was quantified for each tissue core as a percentage (CD34-positive area/area of tissue core). The mean CD34 scores were 0.24%, 0.40%, 1.30%, 2.33%, 2.64%, and 3.44% for normal breast tissue, in stage IIA, IIB, IIIA, IIIB, and IIIC breast cancer tissue cores, respectively (p < 0.0001). The mean CD34 scores were 0.70% and 2.21% for lymph node-negative and lymph node-positive breast cancer patients, respectively (p < 0.0001).

Conclusions

ImageJ software seems to be an attractive quantitative image analysis tool for diagnostic pathology for immunohistochemistry-based applications because of its capabilities, availability, and ease of use with most image formats. Our results show the feasibility, versatility, and ease of use of ImageJ and CD34 immunohistochemistry for vascular image analysis in breast pathology. Given the prospects of novel lymphatic and vascular endothelium-targeting therapeutics in breast oncology, the practical analysis of combined LEC and BEC density described in this report could enable diagnostic pathologists to apply quantitative vascular image analysis easily in their pathology practice and translational research.     

Expert systems and automatic diagnostic systems in histopathology--a review

In this decade, the pathological information system has gradually been settled in many hospitals in Japan. Pathological reports and images are now digitized and managed in the database, and are referred by clinicians at the peripherals. Tele-pathology is also developing; and its users are increasing. However, in many occasions, the problem solving in diagnostic pathology is completely dependent on the solo-pathologist. Considering the need for timely and efficient supports to the solo-pathologist, I reviewed the papers on the knowledge-based interactive expert systems. The interpretations of the histopathological images are dependent on the pathologist, and these expert systems have been evaluated as "educational". With the view of the success in the cytological screening, the development of "image-analysis-based" automatic "histopathological image" classifier has been on ongoing challenges. Our 3 years experience of the development of the pathological image classifier using the artificial neural networks technology is briefly presented. This classifier provides us a "fitting rate" for the individual diagnostic pattern of the breast tumors, such as "fibroadenoma pattern". The diagnosis assisting system with computer technology should provide pathologists, especially solo-pathologists, a useful tool for the quality assurance and improvement of pathological diagnosis.     

Virtual microscopy: high resolution digital photomicrography as a tool for light microscopy simulation

Recent advances in microcomputers and high resolution digital video cameras provide pathologists the opportunity to combine precision optics with digital imaging technology and develop new educational and research tools. We review recent advances in virtual microscopy and describe techniques for viewing digital images using a microcomputer-based workstation to simulate light microscopic examination, including scanning at low power to select features of interest and zooming to increase magnification. Hardware and software components necessary to acquire digital images of histological and cytological slides, and closely simulate their examination under a light microscope are discussed. The workstation is composed of a MicroLumina digital scanning camera (Leaf Systems, Southborough, MA), light microscope (Olympus Optical Co., Lake Success, NY), Pentium (Intel Corp., Santa Clara, CA) 166 MHz microcomputer configured with 64 megabytes of random access memory (RAM), a MGA Millenium Powerdesk graphics card (Matrox Graphics, Inc., Montreal, Canada) and Photoshop software (Adobe Systems Inc., San Jose, CA) running in a Windows 95 (Microsoft Corp., Redmond, WA) environment. Images with spatial resolutions of up to 2700 x 3400 pixels in 36-bit color, can be displayed simultaneously as distinct images in a montage, or merged into a single composite image file to highlight significant features of a histological or cytological slide. These image files are saved in Joint Photographers Experts Group (JPEG) format using compression ratios of up to 80:1 without detectable visual degradation. The advantages and technical limitations of various workstation components are addressed and applications of this technology for pathology education, proficiency testing, telepathology, and database development are discussed.     

Working at the microscope: analysis of the activities involved in diagnostic pathology

Randell R, Ruddle R A, Quirke P, Thomas R G & Treanor D
(2012) Histopathology  60, 504–510
Working at the microscope: analysis of the activities involved in diagnostic pathology Aims: To study the current work practice of histopathologists to inform the design of digital microscopy systems. Methods and results: Four gastrointestinal histopathologists were video‐recorded as they undertook their routine work. Analysis of the video data shows a range of activities beyond viewing slides involved in reporting a case. There is much overlapping of activities, supported by the ‘eyes free’ nature of the pathologists’ interaction with the microscope. The order and timing of activities varies according to consultant. Conclusions: In order to support the work of pathologists adequately, digital microscopy systems need to provide support for a range of activities beyond viewing slides. Digital microscopy systems should support multitasking, while also providing flexibility so that pathologists can adapt their use of the technology to their own working patterns.