The lead article in the January 2012 issue of CAP Today addresses the pending FDA regulation of whole slide imagers (WSI's). The FDA has concluded dthat these devices are "Class III" medical devices, and as such are subject to considerable federal regulation (compared to Class I and II devices). Depending on your perspective, this is either a good thing for patient safety or the death knell for rapid development, certification and deployment of these devices in the United States, with many companies looking elsewhere for testing and validation).
By way of quick review, Class I devices are lowest risk and require no pre-market notification. Your light microscope is, believe it or not, classified as a Class I device. Class II devices are considered "moderate risk" and are usually based on modifications of prior approved devices or techniques. Class III devices are considered "highest risk" and such devices require premarket FDA approval, quality controls, etc. Automated cytology screeners, for example, are Class III devices. The FDA has said that WSI's belong in this category as well.
It seems somewhat surprising, at least to me, that a technique based on standard light microscopy, with microscopes being essentially unregulated, Class I devices, should be given the "highest risk" Class III rating. Although the rationale for that decision may be difficult to fathom, it has, in fact, been made and is highly unlikely to be reversed.
The fact that the FDA has even been reviewing WSI's and has decided to regulate them as "highest risk" Class III devices, may come as a surprise to most end-user pathologists since the topic of regulation is understandably not a major one at trade shows where vendors try to sell these devices. It certainly isn't a topic the vendors themselves are likely to bring up, at least until now.
Although the FDA has been less than specific in discussing their thinking, they have indicated that they have concerns about image quality when compared to standard light microscopy, and the effect of navigating on a computer screen v. moving a slide on a microscope. It is even unclear whether WSI's might be approved for a certain TYPE of specimen or group of diagnoses and not for other types or groups. Might it be approved for small core biopsies and not for big tissue blocks? Might it not be approved for hematologic malignancies, where the diagnosis often requires viewing large areas at relatively high magnification, something that is more difficult with a WSI? At this point, no one knows. Clinical trials comparing the accuracy of WSI's v. traditional microscopy will be difficult to construct and time consuming to perform, but will likely provide the data to answer these questions.
Given the FDA's pace of action in regard to other issues, it's now expected that it may take up to five years for the first devices to be approved in the United States, with Aperio likely to be among the first. Some companies will most likely concentrate their efforts in Europe where the approval process (and subsequent sales) are likely to be much more rapid.
There are many unanswered questions at this early juncture, but it does seem clear that buying and using a WSI for clinical (not research) diagnosis would not be a prudent move at this point in time. If you are currently using a WSI for primary clinical diagnosis, you had better have "state of the art" (whatever that is!) validation policies in effect, and even then your CLIA or CAP inspection is likely to be problematic. Even when these instruments gain approval, their use for diagnosis at a distance will fall under the highly diverse state laws regarding telemedicine. A topic I covered in one of my early blogs, "Down the Telepathology Rabbit Hole."