The FDA has instructed providers of digital pathology devices to test components of their technology and conduct system-level assessment prior to the submitting of clinical data.
The recommendation comes in a final guidance document unveiled April 20 that provides insight on what technical performance assessment data sponsors should provide ahead of an evaluation of a whole slide imaging system. It updates a draft version issued in February 2015.
WSI systems consist of an image acquisition subsystem that converts the content of a glass slide into a digital image file or a workstation for viewing the digital images.
The document provides a laundry list of the descriptions and test methods that should be included in the technical performance assessment.
For example, it recommends that the applicant’s premarket submission contain a “block diagram” of the investigational device’s sub-components designed for image acquisition and display.
Further, the digital pathology device’s light source consists of a lamp and condenser. Sponsors should provide detailed information, such as the bulb type and its expected lifetime. A recommended test for the “measure the spectral distribution of light incident on the slide” is described in the guidance.
The guidance also describes the testing of various other components, including the slide feeder, digital imaging sensor, image processing software and image review manipulation software.
It also provides recommended system-level assessments of color reproducibility, spatial resolution, focus quality, whole slide tissue quality and stitching error, which is a reference to the technique used to combine thousands of sub-images into a single, digital whole slide image.
Sponsors also should report the typical “turnaround time,” needed for the software to execute a user command, such as panning or zooming, the FDA says.
Incorporating human factors testing to validate the user interface also is recommended. The items that should be included in the test are described in the guidance.
Finally, sponsors should provide information on quality control procedures, as well as a quality control manual.
The guidance does not cover subsequent aspects of the review process related to clinical evaluation of safety and effectiveness.