Implementation of large-scale routine diagnostics using whole slide imaging in Sweden: Digital pathology experiences 2006-2013

Abstract

Recent technological advances have improved the whole slide imaging (WSI) scanner quality and reduced the cost of storage, thereby enabling the deployment of digital pathology for routine diagnostics. In this paper we present the experiences from two Swedish sites having deployed routine large-scale WSI for primary review. At Kalmar County Hospital, the digitization process started in 2006 to reduce the time spent at the microscope in order to improve the ergonomics. Since 2008, more than 500,000 glass slides have been scanned in the routine operations of Kalmar and the neighboring Linköping University Hospital. All glass slides are digitally scanned yet they are also physically delivered to the consulting pathologist who can choose to review the slides on screen, in the microscope, or both. The digital operations include regular remote case reporting by a few hospital pathologists, as well as around 150 cases per week where primary review is outsourced to a private clinic. To investigate how the pathologists choose to use the digital slides, a web-based questionnaire was designed and sent out to the pathologists in Kalmar and Linköping. The responses showed that almost all pathologists think that ergonomics have improved and that image quality was sufficient for most histopathologic diagnostic work. 38 ± 28% of the cases were diagnosed digitally, but the survey also revealed that the pathologists commonly switch back and forth between digital and conventional microscopy within the same case. The fact that two full-scale digital systems have been implemented and that a large portion of the primary reporting is voluntarily performed digitally shows that large-scale digitization is possible today.

Keywords: Clinical routine; digital pathology; digital pathology workflow; remote work; whole slide imaging.

Figure 1

Combined work flow when adding scanning and digital diagnostics. Currently, a conventional and a digital work flow are maintained simultaneously. The red meander-like track belongs to the conventional work flow; whereas, the blue track represents the work flow envisioned with full digitization. Each activity is categorized as having either high or low human involvement, in order to highlight potential benefits from automation

Figure 2

Distribution of histopathological cases diagnosed digitally according to the responses in the survey asking pathologists with access to a digital workstation in Linköping and Kalmar

Figure 3

Responses asking pathologists in Kalmar and Linköping with access to a digital workstation: “How often do you use the following digital tools?”

Figure 4

Responses asking pathologists in Kalmar and Linköping with access to a digital workstation: “When diagnosing digitally to what extent do you agree with the following statements?”