Preparing for The Pathology Digital Revolution: Implementation of Whole Slide Imaging

John Paul Graff, DO, Assistant Professor of Pathology and Laboratory Medicine
Lorne Holland, MD, Informatics Fellow

Background

Recent advances in technology have increased interest in using whole slide imaging (WSI) for patient care. As this technology moves from primarily research and/or teaching use to the clinical setting, several operational and regulatory issues must be address for successful implementation.

Discussion of Best Practice

• What is the intended use? Common clinical uses include consultative telepathology, intraoperative diagnosis and primary diagnosis.
• What type of slides will be scanned? Most scanners are optimized to handle standard H&E slides but may or may not be able to handle wet slide (e.g. intraoperative slides, peripheral smears) or alternate slide sizes (e.g. large format).
• How many slides need to be scanned and how quickly? Some uses, like intraoperative diagnosis, may not require large numbers of slides to be scanned. Other uses, like primary diagnosis, make require a large number of slides to be scanned each day. Most modern devices can scan a slide in about a minute, but the real total time per slide can vary based on the amount of preparatory work needed (labeling slide, loading slides/cassettes, rate of failure to scan, manual data input to the system, and technical limitations, etc.).²
• What type of slides are being scanned? Cytology slides require scanners than can examine slides along the z-axis (i.e. depth of field or focus plane). Hematopathology slides may require use of high-power (i.e. oil immersion) magnification and can be difficult to implementation due to reliability issues. Slides that use fluorescent staining methods also require special scanners with specific light sources.
• What companion software is needed? Additional software may be necessary if you intend to integrate cases into a clinical workflow, either through an LIS or as a stand-alone process. Computerized analysis of the images also typically requires additional software.
• Who much server space / data storage is needed? This can become an expensive component as this storage is required to be rapidly accessible and HIPAA compliant. Limited by the current technology, and depending laboratory size hundreds of gigabytes of space will be needed per day for normal operations, as one slide can easily approach 1 gigabyte.
• What is the budget? Cost of scanners varies greatly and the fastest, most expensive one is not always the best choice. One that balances meeting technical needs and cost is the best solution. Additional direct (such as computers and monitors) and indirect costs (such maintenance and labor) should not be forgotten.

Like many changes, adoption of WSI is not a purely technical challenge, but also includes human elements as well. Pathologists, staff and other clinicians must be “on board” for implementation to be successful. A number of particular pain points have been identified as particularly important and are listed below.¹

• Lack of sufficient training with the technology. Each user will have their own baseline level of ability and training should be individualized based on how they will use the system and that baseline aptitude. This is perhaps the key issue to address during implementation as it can exacerbate or ameliorate the concerns that follow.
• Potential increased time to review cases. New processes can often be more time consuming than old ones and such is true of the transition from microscope to computer. A “lack of faith” in the technology may also cause more thorough review than would be done when using a microscope. Proper training and inclusion of many pathologists in the validation process may lessen the initial concern. As familiarity with a system increases, this concern should be further mitigated.
• Differences in the mechanics and ergonomics. How one uses a computer is fundamentally different than how one uses a microscope. Work stations need to be reconfigured to minimize potential mechanical stress and eye-strain from the new computer-centric workflow. Also, the introduction of ergonomic user interfaces for pathologist is helpful.
• Potential introduction of new artifacts. Pathologists are generally comfortable recognizing and ignoring artifacts caused by standard slide preparation methods. Including as many pathologists in the validation process as possible will help to recognize and verify which artifacts may or may not occur in the new digital process.
• Limited FDA approval for use of WSI for primary diagnosis. The FDA has defined a process to evaluation WSI platforms³ and one platform has already been approved through this process (Philips IntelliSite Pathology Solutions). More platforms will likely follow soon as the path to approval is now better defined.⁴ However, since the Philips solution uses a proprietary image file type, the market may become segmented with poor interoperability as other systems will almost certainly use alternate file types.

Whole slide imaging is no different than other diagnostic tests in that it requires validation prior to clinical use.⁵ Exactly how this validation is performed will vary from institution to institution and based on whether the platform is FDA-approved or not, but a number of important considerations need to be addressed in all cases. ⁶

• Documentation of training of all users on the system for the functions they will perform
• Documenting validation of the entire process for the intended use(s); from slide creating through viewing on a screen
• Obtaining approval from the hospital's medical advisory committee
• Ensuring malpractice insurance includes telepathology services
• Identifying and addressing any regulatory issues around WSI
• Developing downtime procedures to allow patient care to continue if the system is down
• Define the process whereby cases can be deferred to glass slide review
• Engaging surgical colleagues regarding potential impacts to their workflows
• Establishing a quality system to monitor performance, errors and necessary corrective actions

The transition from glass slide to digital workflow in clinical diagnostics is already underway. With the recent first FDA approval of a system for primary digital diagnosis, the pace will only accelerate. As such, pathologists need to become familiar with the challenges to implementing such systems, both technological and human, as well as the necessary components of validation to ensure safe and accurate patient care.

Finally, once these systems are in place, clinician can rapidly have difficult cases sent for second opinion, without the need to physically ship the glass slides, and blocks. Unlike radiology that made this transition to digital diagnostics almost two decades ago, pathology enters the digital age with more sophisticated and advanced tools. Like radiology, which is viewable by most clinical teams through the EMR, patient's slides will now be viewable providing both clinician and patient's access to information previously only ascertained via physical microscopic analysis. As this sector of digital pathology grows we will see increased innovations in computer vision, AI technologies, pathology workflows, and less demand on FTEs and laboratories in the management of moving glass slides. The results of these innovations should lead to faster and more precise patient care with more standardized and reproducible diagnoses.

References:

• Evans AJ, Salama ME, Henricks WH, Pantanowitz L. Implementation of Whole Slide Imaging for Clinical Purposes: Issues to Consider From the Perspective of Early Adopters. Arch Pathol Lab Med. 2017 Jul;141(7):944-959.
• Campbell WS, Lele SM, West WW, Lazenby AJ, Smith LM, Hinrichs SH. Concordance between whole-slide imaging and light microscopy for routine surgical pathology. Hum Pathol. 2012 Oct;43(10):1739-44.
• DPA Recommends whole Slide Imaging Manufacturers Submit De novoApplications to the FDA for Primary Diagnosis in the United States. Available from: http://www.prweb.com/releases/2016/01/prweb13163307.htm [Last accessed 10/24/2018]
• Abels E, Pantanowitz L. Current State of the Regulatory Trajectory for Whole Slide Imaging Devices in the USA. J Pathol Inform. 2017 May 15;8:23.
• Pantanowitz L, Sinard JH, Henricks WH, Fatheree LA, Carter AB, Contis L, Beckwith BA, Evans AJ, Lal A, Parwani AV; College of American Pathologists Pathology and Laboratory Quality Center. Validating whole slide imaging for diagnostic purposes in pathology: guideline from the College of American Pathologists Pathology and Laboratory Quality Center. Arch Pathol Lab Med. 2013 Dec;137(12):1710-22.
• Evans AJ, Kiehl TR, Croul S. Frequently asked questions concerning the use of whole-slide imaging telepathology for neuropathology frozen sections. Semin Diagn Pathol. 2010 Aug;27(3):160-6.