CDRH Drafts Guidance on Quantitative Imaging
Posted 18 April 2019 | By
Manufacturers looking for premarket submission recommendations for medical devices that generate quantitative imaging values have a new resource as the US Food and Drug Administration’s (FDA) Center for Devices and Radiological Health (CDRH) released draft guidance Thursday.
CDRH’s proposed recommendations cover the device’s functional description, technical performance assessment and labeling/user information. For devices that include quantitative imaging functions, the recommendations apply to premarket approval applications, humanitarian device exemption applications, 510(k)s, investigational device exemption applications and de novo classification requests.
“Medical imaging is used routinely in hospitals and clinics to assist with the diagnosis and management of patients with a variety of diseases and conditions, by providing visual representations of the internal structures of the body,” CDRH says. “Most medical images are acquired with the intention of qualitative interpretation by a trained physician to identify the presence or absence of a structure or feature.”
Medical devices that include quantitative imaging functions, however, are intended to extract additional information in the form of numerical values compared to clinicians’ qualitative interpretations of medical images. Quantitative imaging values span across several different imaging modalities, intended uses, levels of automation as well as the complexities of the algorithms used for the imaging processing.
Yet the values have also been known to be subject to systematic errors and random variation, which can in turn impact clinical decision-making. CDRH aims to limit these risks with the draft guidance by encouraging greater consistency in the information and technical data provided in support of quantitative imaging functions.
The draft explains how CDRH considers quantitative imaging values to be “objective characteristics measured on a ratio or interval scale,” otherwise described as “measured parameters derived from medical images that have a physical meaning.”
As examples of quantitative imaging values, CDRH points to standard uptake values in nuclear medicine, magnetic resonance (MR) imaging and computed tomography and relaxometry in MR.
The three overarching areas of recommendations on what to include in premarket submissions to CDRH are further detailed in the subsets included under each category. For device function description, the draft guidance lists five pieces of information CDRH recommends including. The draft guidance also proposed 10 best practices for manufacturers to perform technical performance assessments, starting with defining relationships between the quantitative imaging functions and the measure/use conditions.
CDRH also touches on fully automated functions’ considerations, which include aiding user understanding.
“Device labeling should include sufficient information for the end user to obtain, understand and interpret the values provided by the quantitative imaging function,” CDRH says. CDRH identifies five elements in labeling, including measure and algorithm input descriptions, performance specifications and instructions for image acceptance or quality assurance, that must be in premarket submissions.
In addition to premarket submission information, the draft guidance offers an overview of potential sources of errors in quantitative imaging values. Such errors may result from acquiring medical images, patient characteristics and image processing algorithms.