Testing an equipment for MRI Compatibility

[shiftkoji]

I'm trying to do some project planning around testing our device for MRI safety. It's a class II device, but not an implantable. It's a monitoring device that would be outside the MRI machine, but in the room at the same time. It's something our customers have been asking about.

I've had trouble getting responses from test labs about this, so while I'm waiting I thought I would post here. Does anyone have any experience with testing to determine if it is MRI-conditional or MRI-safe?

What was the cost? How involved was testing?

I have not seen hard-limits for testing regarding this, and seems to be more judgement based on test conditions. If someone knows otherwise, I'd love to be pointed in the right direction.

 

[Sam Lazzara]

I do a lot of work related to MRI testing on behalf of my clients, for non-active implantable devices mostly. I have searched the globe for test labs and have obtained quotes on numerous occasions. My current recommendation based on general affordability (compared to the others) and excellent customer service is a test lab in Canada called MRIdt.

Disclaimer - I have no connection with this lab other than being a satisfied customer.

 

[Sam Lazzara]

Here are some random notes regarding MRI compatibility testing.
Even though "implants" are mentioned below, the same general principles apply to any device brought into the MRI suite.

Testing can be replaced by a justification for non-magnetic materials.

Applicable Standards (versions listed may not be the latest)

ASTM F2052:2015
Standard Test Method for Measurement of Magnetically Induced Displacement Force on Medical Devices in the Magnetic Resonance Environment

ASTM F2119:2007 (2013)
Standard Test Method for Evaluation of MR Image Artifacts from Passive Implants

ASTM F2182:2011a
Standard Test Method for Measurement of Radio Frequency Induced Heating near Passive Implants During Magnetic Resonance Imaging

ASTM F2213:2006 (2011)
Standard Test Method for Measurements of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment

ASTM F2503:2013
Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment

US FDA Guidance:2014
Guidance for Industry and FDA Staff – Establishing Safety and Compatibility of Passive Implants in the Magnetic Resonance (MR) Environment 


Example Design Input Requirement for Implant
7.3.3 Implant Magnetic Resonance Imaging (MRI) Compatibility: Implant shall be labeled as “MR Conditional”, meaning it has been demonstrated to pose no known hazards in a specified MR environment with specified conditions of use. MR-imaging artifacts where the device is deployed is acceptable if disclosed in IFU.
MR-Conditional Labeling (ASTM F2503) requirement is for IFU to disclose specified MRI environment for which implant can be safely scanned. Determine MRI-compatibility labeling requirements by testing compatibility with 3-Tesla MRI system to obtain experimental data as described below.
· Magnetically Induced Displacement Force per ASTM F2052
· Magnetically Induced Torque per ASTM F2213
· Heating by RF Fields per ASTM F2182
· Image Artifact per ASTM F2119

 

[Ajit Basrur]

Great advise, Sam. Much appreciated

 

[evanomics]

Testing can be replaced by a justification for non-magnetic materials.

Sam - is there an ISO standard/guidance or other reference that says you can justify based on materials? I have a non-implantable product with a small non ferrous foil that we would like to avoid doing MRI compatibility testing on if possible.

 

[Sam Lazzara]

Sam - is there an ISO standard/guidance or other reference that says you can justify based on materials? I have a non-implantable product with a small non ferrous foil that we would like to avoid doing MRI compatibility testing on if possible.

From FDA Guidance 2021 - Testing and Labeling Medical Devices for Safety in the Magnetic Resonance (MR) Environment:

MR Safe—“a medical device that poses no known hazards resulting from exposure to any MR environment. MR Safe medical devices are composed of materials that are electrically nonconductive, nonmetallic, and nonmagnetic”

By definition, MR Safe medical devices are composed of materials that are electrically nonconductive, nonmetallic, and nonmagnetic. For the purposes of determining the safety of a medical device in the MR environment, a medical device can be defined as electrically nonconductive if the conductivity is less than 2 S/m, given that the conductivities of some human tissues reach this value. Most plastics, glass, and many ceramic materials are MR Safe. A scientific rationale (e.g., including information about the electrical conductivity and magnetic properties of the device material(s)) rather than testing can be used to support an MR Safe designation. Small metallic devices such as metal markers or polymer devices containing small metal radiopaque markers are not MR Safe because they contain metal and should be labeled MR Conditional. However, depending on the metal used, the MR Conditional labeling can be developed using a scientific rationale rather than testing.

Electrically active medical devices should be designated either MR Conditional or MR Unsafe, but not MR Safe because they contain electrically conductive components.

My opinion: any devices that contain metal (whether non-ferrous or not) cannot be claimed to be MR Safe without test data per the applicable ASTM standards. After the testing is completed, I suspect the manufacturer will end up claiming MR Conditional with statements explaining the conditions.

I have attached the FDA guidance document and their associated webinar slide deck.

 

[Raghava]

From FDA Guidance 2021 - Testing and Labeling Medical Devices for Safety in the Magnetic Resonance (MR) Environment:

MR Safe—“a medical device that poses no known hazards resulting from exposure to any MR environment. MR Safe medical devices are composed of materials that are electrically nonconductive, nonmetallic, and nonmagnetic”

By definition, MR Safe medical devices are composed of materials that are electrically nonconductive, nonmetallic, and nonmagnetic. For the purposes of determining the safety of a medical device in the MR environment, a medical device can be defined as electrically nonconductive if the conductivity is less than 2 S/m, given that the conductivities of some human tissues reach this value. Most plastics, glass, and many ceramic materials are MR Safe. A scientific rationale (e.g., including information about the electrical conductivity and magnetic properties of the device material(s)) rather than testing can be used to support an MR Safe designation. Small metallic devices such as metal markers or polymer devices containing small metal radiopaque markers are not MR Safe because they contain metal and should be labeled MR Conditional. However, depending on the metal used, the MR Conditional labeling can be developed using a scientific rationale rather than testing.

Electrically active medical devices should be designated either MR Conditional or MR Unsafe, but not MR Safe because they contain electrically conductive components.

My opinion: any devices that contain metal (whether non-ferrous or not) cannot be claimed to be MR Safe without test data per the applicable ASTM standards. After the testing is completed, I suspect the manufacturer will end up claiming MR Conditional with statements explaining the conditions.

I have attached the FDA guidance document and their associated webinar slide deck.

Hi Sam, Is the MRI marking only for Medical devices or can we also claim this for non med devices? I am working on some non medical system covers that go into the MRI environment and was looking if I can use the MR safe symbol or not. Thanks!

 

[Sam Lazzara]

Hi Sam, Is the MRI marking only for Medical devices or can we also claim this for non med devices? I am working on some non medical system covers that go into the MRI environment and was looking if I can use the MR safe symbol or not. Thanks!

ASTM F2503 applies to the "practice of marking of items that might be used in the magnetic resonance (MR) environment".
It is not specific to medical devices.
So feel free to apply it but I would also review any product-specific MRI standards that might apply to your product based on its intended use.