The Food and Drug Administration (FDA or the Agency), the US regulating authority in the sphere of medical devices has published a guidance document dedicated to testing and labeling medical devices for safety in the magnetic resonance (MR) environment. The document provides an overview of the applicable regulatory requirements and describes the approach to be followed by medical device manufacturers to ensure compliance thereto. However, the authority also mentions that an alternative approach could be applied, provided such an approach complies with the applicable legislation and has been agreed with the authority in advance. Due to the legal nature of the guidance, the recommendations contained therein are non-binding.

MRI Safety Labeling: Key Points 

Under the general rule, an application to be submitted by an entity interested in placing its product on the US market should contain details regarding the labeling to be used. In the course of the initial review, the authority will assess whether the labeling complies with the applicable regulatory requirements set forth under 21 CFR part 801 and other relevant regulations. The authority additionally emphasizes that [the] device labeling should include sufficient information for a healthcare professional to determine whether a device can safely enter the MR environment. In particular, such information should be provided in a separate section “MRI Safety Information”, which should be included in the contents for ease of navigation. Depending on the results of the assessment to be carried out by the manufacturer, the label should contain the appropriate indication “MR Safe”, “MR Unsafe” or “MR Conditional”, together with the respective symbol. The authority encourages the manufacturers to use colored versions of symbols, however, black and white versions are acceptable as well. The Agency also mentions that the manufacturer should ensure the availability of such information even if the label will be no longer available for the patient. For instance, it should be provided on the official website or via phone call. 

The FDA additionally emphasizes that the term “MR Compatible”, which was provided in earlier versions of this guidance, should not be used, as it could result in confusion and misinterpretation. 

According to the guidance, the “MR Safe” mark applies to the products containing materials that are electrically non-conductive, nonmetallic, and nonmagnetic. The document further describes the particular criteria to be applied to determine whether the device in question meets these requirements. Such a determination should be also supported by the appropriate scientific rationale. The authority also provides examples of medical devices containing metal elements – such devices could not be marked “MR Safe”. 

It is also explained that electrically active medical devices should be designated either “MR Conditional” or “MR Unsafe”, but not “MR Safe” because they contain electrically conductive components. 

As described in the guidance, the labeling should contain information addressed to both healthcare professionals and patients. When deciding on the content and format of the information to be provided, the manufacturer should consider the aspects related to the way the device will be used, and also the information that should be available to healthcare professionals applying it. The manufacturer should also take into consideration the particular procedures the device is intended to be used in. The information might include a description of the procedures to be performed, additional instructions, details on monitoring to be conducted, or any other aspects to be considered to ensure the safety of use. Additionally, the manufacturer can provide the details on image artifacts that could take place. 

The labeling information addressed to the patient should also clearly indicate the status of the device. For instance, it should be explicitly stated that the devices marked as “MR Unsafe” should be removed before MR procedures. If the status is “MR Conditional”, it should be a clear instruction to consult with a healthcare professional. According to the guidance, the labeling should state that the patient should duly inform healthcare professionals in advance about the “MR Conditional” device present. In case of implantable medical devices or the ones intended to be fasted to or carried by the patient, the labeling should contain a patient medical device card identifying the device itself and also indicating its MRI safety status. Should the latter be “MR Conditional”, the labeling should either provide detailed enough instructions or references to the source where such instructions could be found. 

The document also contains the Appendices providing additional information regarding the labeling to be used, together with the appropriate examples. 

MR Safe 

According to the applicable regulatory requirements, the device should be marked as “MR Safe” only in case it could be safely taken into any MR environment, and there should be no additional conditions to be considered. In case of any reasonable concerns or contradictions, the “MR Safe” mark should not be used. If a medical device in question is not an implantable medical device, such a mark should be placed on the device itself. At the same time, the scope of information provided should be limited to the details reasonably needed for healthcare professionals to ensure the device is used safely and efficiently. 

The “MR Safe” mark could look like:

MR Unsafe 


In case the device is MR Unsafe and should be kept outside the MRI scanner room, the appropriate mark should be placed to duly inform healthcare professionals and patients. The labeling for such products could also contain the indication of risks associated with the device. As in the previous case, the mark should be placed directly on the device itself (for non-implantable devices). 

The “MR Unsafe” mark should look like:

MR Conditional 

In case the device may enter the MR environment provided the appropriate conditions are met, the appropriate mark should be placed, together with the list of such conditions. These conditions should ensure safety and also be technically feasible in terms of the intended use of the device. The labeling should also contain an indication that the device could impact the accuracy of the results of certain MR procedures or cause harm to the patient. 

The “MR Conditional” mark should look like:

In summary, the present FDA guidance highlights the most important aspects related to the MR safety of medical devices and the way they should be reflected in labeling. The document describes in detail different marks to be placed depending on the MR Safety Status of the device and also provides clarifications and recommendations regarding the additional information the labeling should contain to ensure the healthcare professionals and patients are duly informed regarding the issues associated with the use of a device in question in MR environment. 



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