The FDA has revised its expectations on what information manufacturers should include in premarket submissions for magnetic resonance diagnostic devices.
In draft guidance issued July 14, the FDA says it is updating its recommendations on MRDD applications to reflect changes in standards and legislation since the 1998 release of guidance on the topic.
Equipment affected by the draft document includes nuclear magnetic resonance imaging systems, nuclear magnetic resonance spectroscopic systems and magnetic resonance specialty coils identified by product codes LNH, LNI and MOS, respectively.
The document provides manufacturers with a detailed overview of what they should include in their applications’ device descriptions. Specifically, sponsors should describe and provide a diagram of how each principal component interconnects, to include the following: the magnet, gradient system, radiofrequency system, RF coils, specific absorption rate management and control system, imaging protocols, image processing modules and software.
Manufacturers may use agency-recognized standards to show substantial equivalence to a predicate device in their premarket submissions. Standards from the National Electrical Manufacturers Association, International Electrotechnical Commission, UL (Underwriters Laboratories), International Organization for Standardization, Association for the Advancement of Medical Instrumentation and American National Standards Institute may prove particularly useful in assessing safety and performance, the agency notes.
In terms of performance testing, submissions should document the following imaging quality metrics: signal-to-noise ratio, geometric distortion, image uniformity, slice thickness and spatial resolution. Although no standard test exists for spectroscopy performance, the FDA recommends that manufacturers assess spatial localization accuracy, spectral resolution, signal-to-noise ratio, solvent suppression, decoupling and spectral data processing.
When assessing safety, manufacturers should test the acoustic noise, gradient-induced electric fields, radio frequency energy deposition, and biocompatibility and flammability of patient-contacting materials.
The FDA also recommends that manufacturers provide sample clinical images for all of the coils, pulse sequences and imaging protocols described in the submission in a Digital Imaging and Communications in Medicine, or DICOM, format. “FDA requests that all images be accompanied by a description of the target anatomical site, scan parameters employed and total imaging time,” the guidance says.
For the user or operator’s manual, the FDA recommends the manufacturer address the contraindications, warnings, precautions and general risks associated with the device, and that it includes the following statement: “Caution: Federal law restricts this device to sale by or on order of a physician.”