Frequently asked questions concerning the use of whole-slide imaging telepathology for neuropathology frozen sections
Department of Pathology, Laboratory Medicine Program, University Health Network, Toronto, ON, Canada. Seminars in Diagnostic Pathology
(Impact Factor: 2.56).
08/2010; 27(3):160-6. DOI: 10.1053/j.semdp.2010.05.002
TP involves the provision of pathology services over a distance using the Internet to link pathologists at the "viewing site" with diagnostic material in a "remote site." Robotic microscopes were a mainstay of TP; however, this is now changing with the development of whole-slide imaging (WSI) systems which enable rapid production of digital slides that can be reviewed over a complete range of magnifications with a viewing experience closely replicating that of light microscopy. As such, WSI will undoubtedly become a viable option for pathology departments considering TP for remote frozen section (FS) coverage, and in the future for rapid consultation on difficult cases. For reasons to be discussed below, it may be particularly attractive to use WSI TP for neuropathology frozen sections (NPFS). We have been using WSI TP for primary NPFS diagnoses since 2006. This brief review provides answers to questions that we have frequently been asked about our program. The answers reflect our experience, and it is important to note that our recommendations may not be applicable in all institutions. The reader is directed to the recent literature for more detailed information on WSI as well as a complete description of our TP program.
Available from: Keith J Kaplan
- "The advantages of using WSI for this purpose include access to an entire digitized slide or even an entire case (set of slides), automated scanning, the high resolution of images available for review, rapid interpretation time, and the ability to exploit simultaneous viewing (teleconferencing). The University Health Network (UHN) in Ontario, Canada has extensive experience using WSI for telepathology. UHN is a multi-site academic institution in downtown Toronto, comprising the Princess Margaret Hospital (PMH), Toronto Western Hospital (TWH) and Toronto General Hospital (TGH) which houses UHN's consolidated pathology department. "
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ABSTRACT: Whole slide imaging (WSI), or "virtual" microscopy, involves the scanning (digitization) of glass slides to produce "digital slides". WSI has been advocated for diagnostic, educational and research purposes. When used for remote frozen section diagnosis, WSI requires a thorough implementation period coupled with trained support personnel. Adoption of WSI for rendering pathologic diagnoses on a routine basis has been shown to be successful in only a few "niche" applications. Wider adoption will most likely require full integration with the laboratory information system, continuous automated scanning, high-bandwidth connectivity, massive storage capacity, and more intuitive user interfaces. Nevertheless, WSI has been reported to enhance specific pathology practices, such as scanning slides received in consultation or of legal cases, of slides to be used for patient care conferences, for quality assurance purposes, to retain records of slides to be sent out or destroyed by ancillary testing, and for performing digital image analysis. In addition to technical issues, regulatory and validation requirements related to WSI have yet to be adequately addressed. Although limited validation studies have been published using WSI there are currently no standard guidelines for validating WSI for diagnostic use in the clinical laboratory. This review addresses the current status of WSI in pathology related to regulation and validation, the provision of remote and routine pathologic diagnoses, educational uses, implementation issues, and the cost-benefit analysis of adopting WSI in routine clinical practice.
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ABSTRACT: Intraoperative consultations in neuropathology are often assessed by smear preparations rather than by frozen sections. Both techniques are standard practice for light microscopic examination on site, but there is little data comparing these techniques in a telepathology setting.
Thirty cases of brain tumours submitted for intraoperative consultation at our institution between July and December 2010 were identified in which both frozen section and tissue smear preparations were available for digitization at 20× magnification. Slides were digitized using a Hamamatsu Nanozoomer 2.0 HT whole slide scanner, and resulting digital images were visualized at 1680 × 1050 pixel resolution with NDP. view software.
The original intraoperative diagnosis was concordant with the sign out diagnosis in 29/30 cases; one tumeur was initially interpreted as a high grade glioma but proved to be a lymphoma at sign out. Digitized frozen section slides were sufficient for diagnosis at 10× magnification in 27/30 cases. Digitized tissue smears were sufficient for diagnosis at 10× magnification in 28/30 cases. In two cases tumour was present on the tissue smear but not the frozen section (one case of recurrent astrocytoma, one case of meningeal carcinomatosis). In one case of lymphoma, tumour was present on frozen section only. These discrepancies were attributed to tissue sampling rather than image quality. Examination of digitized slides at higher magnfication (20×) permitted confirmation of mitoses and Rosenthal fibers on tissue smear preparations, but did not change the primary diagnosis. Intra-slide variations in tissue thickness on smear preparations led to variable loss of focus in digitized images, but did not affect image quality in thinner areas of the smear or impede diagnosis.
Digitized tissue smears are suitable for intraoperative neurotelepathology and provide comparable information to digitized frozen sections at medium power magnification.
Available from: archivesofpathology.org
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ABSTRACT: Context.-Digital whole slide imaging is the anticipated future of anatomic pathology, where sign-out of glass slides will be replaced by scanned images. Whole slide imaging has been successfully used in surgical pathology, but its usefulness and clinical application have been limited in cytology for several reasons, including lack of availability of z-axis depth focusing and large file size. Recently, several systems have become available in the United States for whole slide imaging with z-axis technology. Objective.-To determine the accuracy and efficiency of whole slide imaging, as compared with traditional glass slides, for use in cervicovaginal diagnostic cytology. Design.-Eleven cervicovaginal cytology cases (ThinPrep and SurePath) scanned at ×20, ×40, and ×40 z-stack magnifications using the BioImagene iScan Coreo Au 3.0 scanner were evaluated by 4 cytotechnologists and 3 pathologists in a blinded study. Different magnification scans were recorded as separate cases and presented in a randomized sequence. Corresponding glass slides were also reviewed. For each case, the diagnoses and total time to reach each diagnosis were recorded. Results.-Diagnostic accuracy was higher and average time per case was lower with glass slides as compared with all digital images. Among the digital images, the ×40 or ×40 z-stack had the highest diagnostic accuracy and lowest interpretation time. Conclusions.-Whole slide imaging is a viable option for the purposes of teaching and consultations, and as a means of archiving cases. However, considering the large file size and total time to reach diagnosis on digital images, whole slide imaging is not yet ready for daily cervicovaginal diagnostic cytology screening use.
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