On February 25, 2015, The Food and Drug Administration (FDA) announced the availability of a draft guidance entitled “Technical Performance Assessment of Digital Pathology
Whole Slide Imaging Devices”. This draft guidance provides industry and Agency staff with recommendations regarding the technical performance assessment data that should be submitted for regulatory evaluation of a digital whole slide imaging (WSI) system. This draft guidance is not final nor is it in effect at this time.

The last decade has seen significant technology advances in the evolution of WSI with the ability to rapidly digitize large numbers of slides automatically and at high resolution. Many applications unique to digital pathology have emerged and, as a result, WSI is increasingly being used in both clinical and research areas.

The Digital Pathology Association (DPA) commends the FDA for the development and release of this draft guidance and for recognizing the significance of this breakthrough technology by taking this important step. The draft guidance establishes an approach for characterizing the technical aspects that are relevant to WSI performance for their intended use and that are important in determining their safety and effectiveness. The DPA anticipates that this draft guidance and other yet-to-be published guidance documents will help clarify the agency’s expectations for WSI regulatory submissions, enabling increased access and wide scale adoption of Digital Pathology for clinical use in the US.

The draft guidance describes how manufacturers should characterize their WSI systems for clinical use. This is a very cohesive and comprehensive view of all of the components of digital pathology systems, both at the component and systems levels. The document lists the components of a whole slide imaging system and goes on to describe each of the components, including slide feeder, light source, imaging optics, mechanical scanner movement, digital imaging sensor, image processing software, scanning methods, image file formats, image review manipulation software, computer hardware, and displays. Another important aspect of the guidance is the discussion surrounding a framework of a typical system-level test and the items that a usability validation test report should include. The draft guidance is detailed in listing several critical line items that the vendors should consider when providing data for regulatory evaluation of digital WSI systems. The approach that FDA taking is consistent with what has been done in other industries, including leveraging existing standards called out in the draft guidance. It is evident from this document that FDA has learned much about digital pathology technology over the past several years.

Many manufacturers have been working with the FDA over the last several years on the issues outlined in the draft guidance document.  DPA commends all the vendors who have met with the FDA and worked collaboratively toward a mutual understanding of the technological aspects that are important to achieving clinical safety and effectiveness of WSI and improved patient care.  While this type of characterization could result in overhead to manufacturers that are seeking FDA clearance or approval, at least we can be assured that the same standards will be applied to all applicants.  As a result of the draft guidance, there exists a clearer set of expectations.

The guidance document also sends important signals to the public about the FDA’s willingness to establish a more defined and predictable regulatory path, and demonstrates their ability to align toward such goals. It is evident from many studies and proven applications of this technology around the world that WSI is an enabling technology that promotes better patient care.

The DPA, including its members of manufactures and pathologists, intend to submit detailed and specific comments to the FDA related to the content of the draft guidance during the specified comment period. The DPA, pathology community and the digital pathology industry look forward to working together with FDA to obtain further guidance regarding clinical and non-clinical analytical study designs and an even more precise definition of what constitutes a WSI system. This document and the resulting public discussion is a promising start to this important regulatory process.