The article highlights the aspects related to clinical images to be submitted by the applicant and also describes the approach to be applied concerning modifications to medical devices covered by the scope of the guidance.

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The Food and Drug Administration (FDA or the Agency), the US regulating authority in the sphere of healthcare products, has published a guidance document dedicated to the submission of premarket notifications for magnetic resonance diagnostic devices (MRDDs).

The document provides an overview of the applicable regulatory requirements, as well as additional clarifications and recommendations to be taken into consideration by medical device manufacturers and other parties involved to ensure compliance with it.

At the same time, provisions of the guidance are non-binding in their legal nature, nor are they intended to introduce new rules or impose new obligations.

Moreover, the authority explicitly states that an alternative approach could be applied, provided such an approach is in line with the respective legislation. It has been agreed with the authority in advance.

Clinical Image Submission

First of all, the authority states that when introducing a new system, it is mandatory to provide the FDA with clinical images that demonstrate the diagnostic capabilities of the system in question.

These images validate the performance of various pulse sequences. If a single pulse sequence finds application across multiple clinical protocols, its sample images should delineate its ability to produce the desired contrast in every protocol.

As explained by the authority, a scientific rationale accompanied by sample images should suffice for a pulse sequence used across several protocols.

The FDA requires that these images be in electronic DICOM format. Furthermore, the authority additionally emphasizes the importance of erasing any patient-specific data before submission.

Every image should be accompanied by details about the target anatomical site, scan parameters used, and total imaging time.

However, it is important to mention that there is an alternative to submitting the entire image set – instead, the applicant can submit a statement from a US-certified radiologist affirming the diagnostic quality of the images.

This statement should describe the sequences and anatomical areas the radiologist examined. If there were any issues with image quality or evaluation, these should be thoroughly addressed. Alongside the statement, a small set of representative clinical images should be provided.

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Device Modifications and 510(k) Submissions

The scope of the guidance also covers the aspects related to modifications to MRDDs. According to 21 CFR 807.81(a)(3), any modification to a device that could potentially impact its safety or its intended use necessitates a new 510(k) submission.

The FDA has provided a non-exhaustive list of modifications that would typically require this. According to the document, the include the changes to:

  • Main Static Magnetic Field: Alterations here can affect the device’s safety and efficacy by changing the system’s resonant frequency.
    Such modifications need testing for signal-to-noise ratio (SNR), geometric distortion, and image uniformity. A measurement of the magnetic field’s homogeneity and stability over extended periods is also required.
  • Gradient System: Changes to this system can impact the MRI system’s safety and efficacy by influencing the Peripheral Nerve Stimulation (PNS) potential, slice selection efficacy, and the system’s acoustic output.
    Such alterations require assessments of geometric distortion, slice profile thickness, and the system’s acoustic output. PNS control changes should also be documented.
  • RF Body Transmit Coil: Modifications to this coil can affect the MRI system’s safety and efficacy by altering the Radio Frequency (RF) energy output. Testing for RF energy deposition, SNR, and image uniformity is necessary for such changes.
  • Changes in the architecture of transmit coils other than the RF body transmit coil can significantly impact the MRI system’s safety and efficacy.
    Thus, testing for RF energy deposition, coil surface heating, SNR, and image uniformity is necessary. However, changes in the material type or composition for non-patient contacting coil housing typically don’t need a new 510(k) submission.
  • RF Receive Coils: Introducing a new RF receive-only coil is a significant design modification.
    Such changes should be tested for SNR, image uniformity, coil surface heating, and biocompatibility.
  • Pulse Sequences: Introduction or modification of pulse sequences might require a 510(k) submission, especially if they significantly impact the device’s safety or efficacy.
    For instance, introducing a metal artifact reduction pulse sequence would necessitate a new 510(k) submission, complete with performance data.
  • Protocols: Changes to protocols might need a 510(k) submission. For example, adding a pediatric epilepsy foci identification protocol would typically require a new 510(k) submission.
    Factors to consider include changes to the target anatomical area, contrast characteristics, and coil restrictions. However, merely re-ordering existing pulse sequences within a protocol wouldn’t necessitate a new 510(k).


In summary, according to the guidance, a new 510(k) is not mandatory when adding a protocol to a new device model, provided the protocol has been cleared in another model by the same manufacturer, and both models share technological characteristics. In addition to this, the document outlines the key criteria to be taken into consideration when determining whether the modifications introduced necessitate a new 510(k).

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