Validation vs. Verification for Whole Slide Imaging (WSI) is it Really a Grudge Match?
Q: My practice would like to start using Whole Slide Imaging for Primary Diagnosis. Does my lab have to undergo verification or validation? What’s the difference between Validation and Verification for Whole slide imaging?
A: The CAP’s definition of validation is: “…Validation:…the process used to confirm with objective evidence that a laboratory developed or modified FDA-cleared/approved test method or instrument system delivers reliable results for the intended application.”
Their definition of verification is: “…Verification….the process by which a laboratory determines that an unmodified FDA- cleared/approved test performs according to the specifications set forth by the manufacturer when used as directed.”
So validation is the process for laboratory developed tests or FDA test systems that have been modified. Verification is the process for FDA approved systems used according to the manufacturer. There is only one WSI system that is FDA cleared in the USA, the Philips IntelliSite Pathology Solution. This system includes the Philips UF Scanner, Philips Display (Viewer), Philips Image Management System, and the monitors used by Philips in the FDA application (Barco, medical grade). **Note of importance - The Philips system is only approved for formalin fixed paraffin embedded H&E slides.
If a laboratory uses another viewer, image management system or monitor with the Philips scanner, it is now an FDA modified system and the laboratory must validate the same way as they would if they were using any other WSI system. The CAP’s definition of the modification of an FDA test is included at the end of this blog. But even if a laboratory uses the FDA approved system according to the manufacturer, it must still undergo a process to ensure the accuracy of the system within each laboratory. Philips states in its FDA letter that the “PIPS is not intended for use with frozen section, cytology, or non-FFPE hematopathology specimens.” Any of these specimens would still require a laboratory to validate the system for those specimen types the same as they would if they were to use any other WSI solution.
Q: What do the CAP Accreditation Checklists Say about Verification or Validation of WSI?
A: The CAP’s Lab General Checklist August 2018 revisions state:
“GEN.52920 Whole Slide Imaging System Validation/Verification Phase I
The laboratory validates or verifies whole slide imaging systems used for clinical diagnostic purposes by performing its own studies, including approval for use by the laboratory director (or designee who meets CAP director qualifications) before the technology is used for the intended diagnostic purpose(s).
NOTE: The specific components of validation or verification studies are left to the discretion of the laboratory. The approval or clearance of whole slide imaging systems by the FDA does not obviate the need for individual laboratories to verify the performance of these systems for the specific intended diagnostic purposes.
As general guiding principles, the validation or verification process should: “Closely emulate the real-world clinical environment and involve specimen preparation types and clinical settings relevant to the intended use(s); Be carried out by a pathologist(s) adequately trained to use the system; Assess intraobserver concordance between digital and glass slides; Encompass the entire whole slide imaging system, with reevaluation if a significant change is made to a previously validated or verified system. “
Summary for Implementing WSI Imaging for primary diagnosis is: The Checklist summarizes the CAP Guidelines for Implementing Whole Slide Imaging which are that a) the lab must conduct its own studies of accuracy, b) the Laboratory Medical Director must be involved and sign off on the studies, c) the study must emulate the intended use and clinical settings, d) that pathologists be adequately trained, e) that intra-observer concordance between glass and digital be assessed, f) that the study encompasses the entire system and g) revaluation takes place if there is a significant change, like a new scanner.
The complete CAP guidelines for implementing WSI can be found below.
Q: What does it mean to modify an FDA approved/cleared test or test system?
A: This is the CAP’s definition: “Any change to the manufacturer's supplied ingredients or modifications to the assay as set forth in the manufacturer's labeling and instructions. It may include a change to specimen type, instrumentation or procedure that could affect its performance specifications for sensitivity, specificity, accuracy, or precision or any change to the stated purpose of the test, its approved test population, or any claims related to interpretation of the results.”
For example, if a practice decided it was not necessary to purchase medical grade monitors to perform primary diagnosis on WSI, this would constitute a modification; and thus, a validation study would need to be performed.
Q: Is it easier to verify an FDA cleared test system for primary diagnosis with WSI or to validate a Lab developed WSI test system or a modified FDA cleared test system?
A: The verification procedure for an FDA cleared test system will depend upon the instructions from the manufacturer and will be depend on the Lab Medical Director’s determination that the test system is accurate. A Lab Medical Director may likely elect to follow the CAP Guidelines for WSI. In which case, the amount of effort for either verification or validation would be the same.
Q: In the event of a malpractice lawsuit involving a diagnosis performed WSI, is a pathologist better protected using an FDA cleared system?
A: In general, the pathologist or laboratory would still be responsible for a misdiagnosis, no matter the means the diagnosis was rendered. In the event of a misdiagnosis using an FDA cleared WSI system, it is unclear to what extent, if any, a pathologist would be protected.
REFERENCES
1) Pantanowitz et al, Validating whole slide imaging for diagnostic purposes in pathology: Guideline from the College of American Pathologists Pathology and Laboratory Quality Center. ARPA, 2013 http://www.archivesofpathology.org/doi/pdf/10.5858/arpa.2013-0093-CP http://www.cap.org/apps/docs/membership/wsi_faqs.pdf
CAP WSI Validation Guidelineshttps://www.cap.org/protocols-and-guidelines/cap-guidelines/current-cap-guidelines/validating-whole-slide-imaging-for-diagnostic-purposes-in-pathology
By Maarion Napora At Gestalt, we understand the role of education for physicians and why it is important to have a focus specifically on pathology. It is our goal to provide the proper digital tools and platforms for pathologists to learn how to use the latest technology in their training. PathFlow ’ s Education Module provides academic medical centers and residency programs with leading tools and digital technology to train the next generation of pathologists. Designed to meet the demands of modern techniques, the module offers the ability to develop courses, easily clone and copy courses, and assign teaching lists, images, and tests. You can set the timing for a course, automatically send out messages to remind students of outstanding courses and test deadlines, etc. We support multiple forms of media, including videos, PowerPoint presentations, and word documents. These enable educators to deliver immersive, digital-first learning experiences. The PathFlow Education Module Revolutionizes pathology training by providing a unified platform for interactive learning. Trainees can access a comprehensive library of annotated digital slides, practice diagnosing complex cases, and receive real-time feedback. Professors can easily grade, provide comments and feedback on assessments, and can even assign certificates. The module’s credentialing management capabilities streamline competency assessments, notifications for deadlines, and reminders if not completed, ensuring residents meet rigorous standards while tracking progress seamlessly. We believe education and access to leading technology is the cornerstone of advancing pathology. With PathFlow’s Education Module, we’re empowering academic programs to train confident, tech-savvy pathologists, who will lead the field forward with current skills in available technology informatics.
Spokane, Washington, July 9, 2025 – Gestalt, a leading provider of AI-powered digital pathology solutions, showcased its AI-powered pathology platform, PathFlow, at the Spring 2025 DICOM WG-26 Interoperability Connectathon, confirming its readiness for real-world clinical integration and multi-vendor environments. The Connectathon was co-sponsored by the Digital Pathology Association (DPA) and the European Society of Digital and Integrative Pathology (ESDIP). The event, hosted virtually from January to June and featured at the European Congress on Digital Pathology in Barcelona, brought together over 30 organizations to validate end-to-end workflows, in varying categories, using DICOM standards. The categories included image acquisition, storage, viewing, and AI-driven annotations. Gestalt’s platform stood out as a leader in interoperability, particularly as an Image Display (Viewer). Gestalt’s Viewer successfully displayed images from 8 of 9 different WSI Scanners, demonstrating seamless compatibility with multiple diverse systems such as 3DHISTECH, Grundium, Leica, Hamamatsu and Pramana. This robust performance ensures pathologists can access high-quality whole slide images effortlessly, regardless of the source, streamlining diagnostic workflows. Additionally, PathFlow excelled in displaying annotations from five AI Evidence Creators, including industry leaders like Visiopharm, Hologic, TechCyte and identify.bio, further demonstrating its ability to present structured data for precise diagnostic insights. As an Evidence Creator itself, (AI Annotations), Gestalt showcased its advanced AI capabilities, by analyzing and annotating images from eight scanners. These annotations were successfully transmitted to five different image management archives using standard DICOM Web protocols, highlighting Gestalt’s ability to deliver accurate, standards-compliant AI-driven outputs. This functionality empowers pathologists to integrate AI seamlessly into routine clinical operations, improving efficiency and diagnostic accuracy. “Gestalt’s performance at the Connectathon reflects our dedication to building interoperable, scalable solutions that empower pathologists globally,” said Brian Napora, VP of Innovation, Gestalt Diagnostics. “By investing in open standards, we’re helping lead digital pathology toward a more integrated and intelligent future.” The Connectathon’s rigorous testing environment validated Gestalt’s ability to handle real-world challenges, such as legacy image integration and complex multi-vendor workflows without requiring custom workarounds. Gestalt’s commitment to DICOM standards positions PathFlow as a cornerstone for vendor-neutral, future-ready pathology solutions. About Gestalt Gestalt Diagnostics is a Spokane-based company dedicated to revolutionizing pathology through digital solutions. Founded in 2017, Gestalt provides advanced technology, proven digital expertise, and artificial intelligence to enable pathologists to diagnose diseases faster and more efficiently. The company's PathFlow platform is at the forefront of digital pathology innovation, offering significant improvements in diagnostic accuracy and workflow efficiency. To learn more, visit www.gestaltdiagnostics.com and follow @Gestalt on LinkedIn
July 2025 Digipath Dispatch – Industry news, digital pathology insights, product updates, and events from Gestalt Diagnostics.
Gestalt’s PathFlow and PathCloud unify pathology workflows, enabling seamless, multi-vendor integration for faster, accurate diagnoses.
Discover why digital pathology is gaining momentum and how it’s shaping diagnostics, improving workflows, and addressing workforce challenges in healthcare.
Discover how Lisa-Jean Clifford is helping shape the future of AI in pathology through a new framework designed for safe, scalable clinical integration.
Spokane, Washington, June 17, 2025 – Gestalt, a leading provider of AI-powered digital pathology solutions, today announced the addition of Dr. Renuka Kulkarni, MD, as Chief Medical Officer (CMO). A physician scientist with over 20 years of experience in surgical and digital pathology, Dr. Kulkarni will join the team in guiding Gestalt’s product direction and clinical usability. Dr. Kulkarni brings a rare blend of diagnostic precision and scientific innovation to the organization. Her expertise in breast pathology, immunomarkers, machine learning, and image analysis strengthens Gestalt’s mission to revolutionize diagnostic workflows and clinical decision-making through technology. “Renuka’s addition signals our deepening investment in the future of pathology,” said Lisa-Jean Clifford, President of Gestalt Diagnostics. “Her leadership and experience at the intersection of clinical insight, AI, and enterprise lab operations will ensure our solutions continue to serve both pathologists and the patients they care for.” Before joining Gestalt, Dr. Kulkarni played a pivotal role in developing one of the earliest digital pathology programs at a leading full-service reference laboratory. Her extensive hands-on experience with Gestalt’s solutions, as a customer and direct user for four years, along with image analysis platforms, and combined with her understanding of real-world lab operations, positions her to help bridge the clinical and commercial realms—ensuring the scalability and impact of Gestalt’s solutions. As CMO, Dr. Kulkarni will help shape the development of next-generation diagnostic tools, supporting Gestalt’s mission to enhance diagnostic accuracy, efficiency, and interoperability across health systems worldwide. “I’m honored to join Gestalt at such a transformative moment in digital pathology,” said Dr. Kulkarni. “Together, we have the opportunity to shape solutions that truly serve pathologists and ultimately improve outcomes for patients everywhere.” About Gestalt Gestalt Diagnostics is a Spokane-based company dedicated to revolutionizing pathology through digital solutions. Founded in 2017, Gestalt provides advanced technology, proven digital expertise, and artificial intelligence to enable pathologists to diagnose diseases faster and more efficiently. The company's PathFlow platform is at the forefront of digital pathology innovation, offering significant improvements in diagnostic accuracy and workflow efficiency. To learn more, visit www.gestaltdiagnostics.com and follow @Gestalt on LinkedIn
Date : Wednesday, May 21, 2025 Time : 1:45 PM Location : Auditorium 1, Marriott Eagle Crest Resort (Ann Arbor, Michigan) Session Title : The Long-Term Advantages of Digital Pathology are Only Realized Through True Interoperability We’re proud to announce that Lisa-Jean Clifford , COO & Chief Strategy Officer at Gestalt Diagnostics, and Sumie Edwards (ARUP) will take the stage at the 2025 Pathology Informatics Summit to share key insights into the critical role of interoperability in digital pathology. In this featured session, Lisa-Jean will explore: Why interoperability is the linchpin for scalable, future-ready digital pathology programs How health systems can unlock long-term value and efficiency through seamless integration Real-world considerations for IT infrastructure, workflow design, and cross-platform compatibility Her session will offer a strategic lens into how institutions can achieve meaningful digital transformation, not just implement new tools. About the PI Summit : The Pathology Informatics Summit is a premier annual event for professionals at the forefront of digital pathology, laboratory medicine, AI, and healthcare data innovation. It brings together leading physicians, researchers, and informaticists to discuss the rapidly evolving field. Mark your calendar for May 21 at 1:45 PM to hear Lisa-Jean share her vision for a more connected and impactful future in pathology.
Date : Thursday, May 22, 2025 Time : 9:00 AM – 12:00 PM Location : Auditorium 1, Marriott Eagle Crest Resort (Ann Arbor, Michigan) Panel Title : API Focus Session: Expert Panel on LDT Regulation Overhaul and Data Challenges in Pathology Informatics Join Lisa-Jean Clifford , COO & Chief Strategy Officer at Gestalt Diagnostics, for an important panel discussion at the 2025 Pathology Informatics Summit alongside top voices in the field of pathology informatics. This focus session will dive into: The impact of the FDA’s Final Rule on Laboratory Developed Tests (LDTs) Data governance, standardization, and access challenges for AI in pathology The urgent need for broadly sourced datasets to support the next generation of clinical AI models Panel Moderator : Ulysses Balis, MD Expert Panelists : Victor Brodsky, MD – Washington University School of Medicine, St. Louis Lisa-Jean Clifford – Gestalt Diagnostics Bruce Friedman, MD Ronald Jackups, MD, PhD – Washington University School of Medicine, St. Louis Amrom Obstfeld, MD, PhD – Children’s Hospital of Philadelphia Michelle Stoffel, MD, PhD – University of Minnesota J. Mark Tuthill, MD – Henry Ford Health System This dynamic session includes two panel discussions followed by open Q&A: The FDA’s Final Rule on LDTs The Growing Crisis of Limited AI Training Data in Pathology Why it matters : With regulatory landscapes shifting and AI innovation surging, this session offers a rare chance to hear from experts shaping the future of diagnostics, data ethics, and clinical technology adoption. Don’t miss this opportunity to learn from Lisa-Jean and fellow leaders who are building the next chapter of pathology informatics.
Spokane, Washington, April 28, 2025 – Gestalt, a leading innovator in AI-powered digital pathology solutions, announced the completion of a $7.5 million Series A financing. The round was led by Cowles Ventures, TVF Funds, Inland Imaging Investments, KickStart Funds, and prominent angel investors from the Pacific Northwest. Gestalt’s PathFlow® platform is used by leading healthcare, academic medical centers, and research organizations. Customers implement PathFlow as their preferred solution because it integrates seamlessly into their existing laboratory information systems, enabling faster, more accurate diagnoses and improving access to expert consultation, education, and research—regardless of location. "PathFlow is transforming pathology by leveraging robust digital workflows and AI algorithms to support scoring of key biomarkers. This enables organizations to accurately match patients to known therapies and generate rich datasets for research and new drug development," said Dan Roark, CEO, Gestalt. "Our technology is designed to improve patient outcomes by enabling faster, more accurate diagnoses and broadening access to clinical expertise." This new funding will facilitate broader market adoption and increased profitability. The capital will be used to expand the company’s customer base, enhance AI capabilities, and pursue FDA clearance. This comes at a critical moment, with rising cancer rates and a declining number of practicing pathologists intensifying the need for scalable, digital-first diagnostic solutions. “We are incredibly grateful for the continued support from our investors,” Roark added. “This funding allows us to expand on the solid foundation we’ve built. We’ve already streamlined how pathologists navigate fragmented systems by creating PathFlow, a unified platform for viewing pathology cases digitally and collaborating with leading experts in real-time without the need to ship specimens. Now, we’ll accelerate innovation and scale our reach to meet the growing demands of modern pathology.” Gestalt is at the forefront of a critical shift in diagnostic medicine, helping transform pathology from a manual, microscope-based process to a scalable digital solution leveraging artificial intelligence tools — like the digital transitions already seen in radiology and cardiology. The company’s platform not only improves diagnostic speed and precision which is critical for cancer patients who can wait for days to weeks or more for a diagnosis, but also unlocks AI-powered insights that enable: Biomarker scoring to support the optimization of patient-therapy matching, Image and data analysis for disease progression studies, And the interoperability that enables pathologists access to valuable aides and insights that streamline their workflows, highlight areas of positivity and reduce missed diagnoses. With this Series A funding, Gestalt remains committed to expanding its impact through the deployment of its’ PathFlow software in healthcare, making high-quality, scalable pathology solutions more accessible to clinicians and researchers worldwide. About Gestalt Gestalt Diagnostics is a Spokane-based company dedicated to revolutionizing pathology through digital solutions. Founded in 2017, Gestalt provides advanced technology, proven digital expertise, and artificial intelligence to enable pathologists to diagnose diseases faster and more efficiently. The company's PathFlow platform is at the forefront of digital pathology innovation, offering significant improvements in diagnostic accuracy and workflow efficiency. To learn more, visit www.gestaltdiagnostics.com and follow @Gestalt on LinkedIn
