FDA Issues Guidance Affecting Digital Pathology Whole Slide Imaging

Whole slide imaging systems are the subject of newly proposed guidance from the FDA addressing “technical performance assessment data that should be provided for regulatory evaluation of digital whole slide imaging (WSI) systems.” WSI involves “digitization of the stained entire tissue specimen on a glass slide” which allows a pathologist to see the slide image on a computer monitor rather than through a microscope. The draft guidance doesn’t focus on clinical submissions but only technical aspects of WSI performance. Before non-technical analytical studies with clinical specimens and clinical studies, the guidance says manufacturers “should first determine the technical characteristics that are relevant to such performance” and provides recommendations for evaluating those technical characteristics. The guidance is “applicable for surgical pathology tasks performed in the anatomic pathology laboratory.” It doesn’t address the non-technical analytical studies or clinical studies that are used to support safety and effectiveness or interpretation of WSI images via mobile platforms. The draft guidance provides a description and test methods for each component of the WSI device—that is, the hardware and/or software that “processes the image signals flowing through the imaging chain.” Such components include the slide feeder, light source, imaging optics, mechanical scanner, digital imaging sensor, image files formats, image processing software, image review manipulation software, and the computer workstation at which the image is displayed. For each component, the guidance lists what information or specifications should be supplied. The guidance also makes suggestions for the system-level assessments and evaluation of other aspects of the system including color reproducibility, labeling, and quality control. Comments must be submitted within 90 days of the Feb. 25, 2015 issue date for the guidance.
Source U.S. Food and Drug Administration, Draft Guidance for Industry and Food and Drug Administration Staff, Technical Performance Assessment of Digital Pathology Whole Slide Imaging Devices, Feb.25, 2015.