The image pyramid system--an unbiased, inexpensive and broadly accessible method of telepathology

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.

Spatial resolution requirements for acquisition of the virtual screening slide for digital whole-specimen breast histopathology

We examined the effect of lateral spatial resolution and reader specialty on the accuracy of detection of breast cancer. The motivation for this pilot study was the need to acquire and display very large data sets in whole-specimen 3D digital breast histopathology imaging. The ultimate goal is to determine the minimum resolution adequate for detection of malignancy. Twenty-three histologic slides were selected from breast pathology cases and digitized at 2 sampling distances (3.2 and 1.9 microm pixels). Images were viewed by 14 pathologists, of whom 5 had breast pathology as their primary specialty. The readers assessed the likelihood of malignancy on a 5-point Likert scale, and provided a provisional diagnosis. For the detection task, sensitivity, specificity, overall accuracy of detection, and area under the receiver-operator curve were calculated. An overall diagnostic score, and scores grouped by malignancy type, were also computed. Outcome measures were examined for significant resolution and specialty effects. Increasing the lateral resolution significantly improved accuracy in diagnosis (P=.004) but no effect was found for detection. Breast specialists achieved significantly higher scores for all outcome measures except specificity. Differences in performance between the 2 groups of readers tended to be greater for the diagnostic task compared to detection, especially at the higher resolution. However, specimen coverage may also be a significant factor. Factors related to the readers may have also affected performance in this study. Based on these results, a more comprehensive study should examine pixel sizes between 0.7 and 1.9 microm.

User attitudes in analyzing digital slides in a quality control test bed: a preliminary study

The pathologist examines suitably stained glass slides through a bright field microscope in order to render histopathological or cytological diagnosis by looking at tissues and cells. Glass slides serve as a permanent record of the patient disease. Over the course of a patient's treatment slides may need to be reviewed at other institutions before treatment can commence. Due to their fragile nature a transportable permanent digital facsimile of the glass slide would be ideal. A digital slide is a set of digital images representing the whole slide normally used by the pathologist, or a significant part of it; it is usually made by a large amount of images, up to thousands, which makes its management difficult. The present paper provides a description of the requirements needed to reproduce glass slides and of the available technological equipment, then the features of the two systems we implemented on different hardware are described, together with those of the digital slide viewer. The viewer was evaluated in two experimental test phases, during which user behaviour and diagnostic reports were measured. Digital slides used in the two experiments were acquired with either system. Possible applications of digital slides are then discussed, including undergraduate and professional education, quality control, and image analysis on full samples as well as on tissue microarrays.

Primary histologic diagnosis using automated whole slide imaging: a validation study

Background

Only prototypes 5 years ago, high-speed, automated whole slide imaging (WSI) systems (also called digital slide systems, virtual microscopes or wide field imagers) are becoming increasingly capable and robust. Modern devices can capture a slide in 5 minutes at spatial sampling periods of less than 0.5 micron/pixel. The capacity to rapidly digitize large numbers of slides should eventually have a profound, positive impact on pathology. It is important, however, that pathologists validate these systems during development, not only to identify their limitations but to guide their evolution.

Methods

Three pathologists fully signed out 25 cases representing 31 parts. The laboratory information system was used to simulate real-world sign-out conditions including entering a full diagnostic field and comment (when appropriate) and ordering special stains and recuts. For each case, discrepancies between diagnoses were documented by committee and a "consensus" report was formed and then compared with the microscope-based, sign-out report from the clinical archive.

Results

In 17 of 25 cases there were no discrepancies between the individual study pathologist reports. In 8 of the remaining cases, there were 12 discrepancies, including 3 in which image quality could be at least partially implicated. When the WSI consensus diagnoses were compared with the original sign-out diagnoses, no significant discrepancies were found. Full text of the pathologist reports, the WSI consensus diagnoses, and the original sign-out diagnoses are available as an attachment to this publication.

Conclusion

The results indicated that the image information contained in current whole slide images is sufficient for pathologists to make reliable diagnostic decisions and compose complex diagnostic reports. This is a very positive result; however, this does not mean that WSI is as good as a microscope. Virtually every slide had focal areas in which image quality (focus and dynamic range) was less than perfect. In some cases, there was evidence of over-compression and regions made "soft" by less than perfect focus. We expect systems will continue to get better, image quality and speed will continue to improve, but that further validation studies will be needed to guide development of this promising technology.

A pixel-based autofocusing technique for digital histologic and cytologic slides

The present paper describes a method for autofocusing specifically studied for the acquisition of digital slides, i.e. full histologic and cytologic slides, utilising low-cost equipment. At first, experimentations with some of the most used focus measures and algorithms have been made, in order to choose the most suitable for histologic and cytologic images. Then, a study of the specific features of digital slides has been preliminarily carried out in order to understand the constraints of the domain. These included the capability of autofocusing in an unattended way on thousands of microscope fields, while fast performance is not a strict requirement. Based on the findings, an algorithm based on a dynamic focus position space, with a variance-based focus measure has been adapted to the specific situation. A qualitative and quantitative evaluation of the proposed algorithm allowed us to show that the proposed algorithm is suitable for the acquisition of digital slides, and furthermore it can be implemented starting from a basic microscope with an inexpensive motorised stage. The algorithm is currently implemented into a complete digital slide acquisition system, which is in turn being used for a Quality Assurance Programme in cervicovaginal cytologic screening.

Development and evaluation of the virtual pathology slide: a new tool in telepathology

BACKGROUND

The Virtual Pathology Slide is an interactive microscope emulator that presents, via the Internet or CD-ROM, a complete 15.53 mm x 11.61 mm digitalized tissue section. The Virtual Pathology Slide mimics the use of a microscope in both the stepwise increase in magnification (from 16x up to 2000x) and in lateral motion in the X and Y Cartesian directions. This permits a pathologist to navigate to any area on a slide, at any magnification, similar to a conventional microscope.

OBJECTIVE

The aim of this study was to assess the diagnostic accuracy and acceptability of the Virtual Pathology Slide.

METHODS

Ten breast needle core biopsies were randomly selected and presented to 17 pathologists or trainee pathologists with at least 2 years experience in pathology practice. Participants were required to examine each case online and provide a diagnostic classification using online feedback forms. The recorded data permitted examination of interobserver variability and user satisfaction.

RESULTS

Agreement between original glass-slide diagnosis and consensus diagnosis using the Virtual Pathology Slide was reached in 9 out of 10 slides. Percentage concordance for slides lay in the range of 35.3% to 100% with an average percentage concordance between slides of 66.5%. The average Kappa statistics for interobserver agreement was 0.75 while average percentage concordance amongst participants was 66.5%. Participants looked at an average of 22 fields of view while examining each slide. Confidence: 81.25% of the participants indicated confidence using the Virtual Pathology Slide to make a diagnostic decision, with 56.25% describing themselves as "reasonably confident," 18.75% as "confident," and 6.25% as "very confident." Ease of use: 68.75% reported the system as "easy" or "very easy" to use. Satisfaction: 87.5% of participants expressed satisfaction with image quality, with 43.75% describing the image quality as "adequate," 25% describing it as "good," and 18.75% describing the image quality as "excellent." Pathologists with a working bandwidth greater than 20 kilobits per second found the download speed of the Virtual Pathology Slide "adequate" or better.

CONCLUSIONS

Results from this study show that the Virtual Pathology Slide can be used to make a correct diagnostic decision, and that the system is a realistic alternative to dynamic telepathology.