Comes Digital Pathology.

Abstract

One year ago, it was predicted that the US Food and Drug Administration (FDA) was likely to approve whole slide imaging (WSI) for digital pathology ‘‘within the next few months.’’ Get ready. Digital pathology will soon be the glass slide’s diagnostic companion. On February 25, 2015, the FDA issued its draft guidance for the technical performance assessment of digital pathology WSI devices. When this language is finalized, it will represent the FDA’s ‘‘current thinking’’ on WSI devices. Importantly, the FDA’s guidance is limited, as per its legislatively determined jurisdiction, to only the ‘‘technical performance of WSI systems for regulatory evaluation.’’ It divides the WSI system into 2 parts or ‘‘subsystems:’’ one the imaging ‘‘acquisition subsystem that converts the content of a glass slide into a digital file’’ (essentially the slide scanner; also termed by the FDA image acquisition); and the other the ‘‘workstation environment for viewing the digital images’’ (essentially the computer screen and associated software; also termed by the FDA image display). The FDA’s draft guidance goes into significant detail, and although it includes items with which most pathologists have some familiarity, such as ‘‘physical size of the display available for image visualization’’ and ‘‘touch screen technology,’’ most of the items described and discussed are not typically within the pathologist’s realm, including ‘‘pixel-offset correction,’’ ‘‘luminance stability,’’ and the ominous-sounding ‘‘dark current level.’’ Clearly most of this language is directed at manufacturers, but because WSI is likely to soon be part of the pathologist’s armamentarium, pathologists should pay heed to these guidelines and provide appropriate commentary. Digital pathology is unlikely to replace glass slides any time soon, but glass slides and digital pathology appear destined to be comites diagnosticus.