Whole Slide Imaging of Large Format Histology in Prostate Pathology: Potential for Information Fusion

摘要

We read with considerable interest the contribution written by Alton Brad Farris, MD, and colleagues1 in the April 2017 issue of the Archives of Pathology & Laboratory Medicine, entitled “Whole Slide Imaging for Analytical Anatomic Pathology and Telepathology: Practical Applications Today, Promises, and Perils.” They have led us, a transnational group of closely collaborating pathologists, urologists, oncologists, engineers, and informaticians, to some considerations on our past and current role in this new era of digitalization of glass slides, that is, whole slide imaging (WSI) of genitourinary neoplasms, in particular, of prostate pathology.2,3This new era of WSI requires knowledge of previous studies that contributed to the current use and role of virtual slides and quantitative tissue analysis, for instance, in prostate cancer detection and grading, as well as in characterization of high-grade prostatic intraepithelial neoplasia and malignancy-associated changes.2 In the past 20 to 30 years, the technologic advancements have reached the point that we can obtain a virtual slide in the range of megabytes to gigabytes accessible, even in tablets and cell phones, for sharing, as well as for joint evaluation in a multidisciplinary setting, including quantitative image analysis.2 Evaluation of prostate histology on virtual slides can offer clues to the diagnostic classification and prognosis and the prediction of response to treatment. To facilitate the collection of quantitative data, machine-vision systems have been developed and Bayesian belief networks and neural networks have been used as diagnostic decision-support systems.2 All these approaches can be seen as the basis for simultaneous, quantitative evaluation of several tissue markers, including immunohistochemical and molecular patterns, in a multiplex system.2There are several advantages currently associated with the digitalization of glass slides in this new era of WSI, including image sharing for teaching, consultation, remote interpretation, and quality assurance.4,5 Additional features are “interactive publication” (similar to online, scientific chats) and image analysis (readers might use measurement systems available in the Web).6 The whole point of a journal article based on WSI is education, that is, the transfer of knowledge, experience, and guidance.7 In our experience, WSI forms an ideal basis for sound communication and represents a major component in medical diagnosis and treatment.There are 2 basic types of glass slides, based on their size and, therefore, of virtual slides derived from them. The most common is the glass slide from material processed in a regular tissue cassette (dimensions, 30 × 25 × 4 mm). The other, far less common, is the glass slide from material processed with a large tissue cassette or megacassette (dimensions, 63 × 47 × 11 mm). The latter is also called large format histology (LFH) or whole mount sections.8 We have applied LFH to basically all types of surgical specimens of bladder, testis, kidney, adrenal gland, penis, and prostate, including their lymphadenectomy. Virtual slides can be obtained from both types of glass slides. The WSI is traditionally based on slides from regular tissue cassettes. In the past few years, we have been able to scan several whole mount sections with a commercially available slide scanner (Figure). This has allowed us to acquire a unique experience in the joint evaluation with clinicians of virtual slides from large-format histology.9,10 Our experience of LFH and WSI is basically related to the field of uropathology. However, it can be performed in all body organs and neoplasms, including breast and its cancers,11 in which LFH can be adopted. To our knowledge, not all commercially available slide scanners allow the users to obtain virtual slides from whole mount sections. However, because of advantages with LFH and WSI,2 we foresee that all the vendors will update their scanners for the purpose of W