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Testing and Labeling of Medical Devices for Magnetic Resonance (MR) Environment Safety and Compatibility

This guidance applies to all medical devices that might be used in the MR environment, including implanted devices, devices fastened to or carried by patients, and devices intended to enter the MR environment. It provides recommendations for MRI safety and compatibility assessments and labeling information for premarket submissions. The guidance excludes MR systems and associated components.

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By ReguVirta
4 min read

What You Need to Know? 👇

What are the three standardized MRI safety categories for medical devices?

Medical devices must be labeled as MR Safe (no known hazards, nonmetallic/nonconductive materials), MR Unsafe (unacceptable risks, must remain outside MRI scanner room), or MR Conditional (safe under specific defined conditions including field strength, SAR limits, and scan duration).

Which medical devices require MRI safety testing according to FDA guidance?

All medical devices that might enter the MR environment require testing, including implanted devices, patient-worn devices (insulin pumps, pulse oximeters), devices anticipated to enter during clinical care, and devices intended for MR use. Testing addresses hazards like heating, displacement force, torque, and image artifacts.

What is the temperature rise acceptance criterion for RF-induced heating in MRI?

For devices near thermally sensitive tissue (brain, eyes, neural tissue), maximum 2°C temperature rise allows 1-hour continuous scanning. For other tissues, 4°C maximum rise permits 1-hour scanning. Higher heating requires manufacturer-determined scan times with cooling periods.

When can passive implants be exempt from RF heating testing?

Passive implants smaller than 2cm in all directions and at least 3cm from other implants don’t require RF heating testing at 3T or less, as they’re expected to generate less than 2°C temperature increase during 1-hour Normal Operating Mode exposure.

What information must be included in MR Conditional device labeling?

MR Conditional labeling must specify static magnetic field strength, maximum SAR values, scan duration limits, RF coil restrictions, patient positioning requirements, image artifact information, and pre/post-scan instructions. A patient device card with safety information and manufacturer contact details is also required.

How should manufacturers report MRI safety test results to FDA?

Test reports must list the hazard addressed, equipment used (including MR system specifications), acceptance criteria with rationale, device configuration tested, pass/fail results, and submission location. Results should follow consensus standards format and include computational modeling documentation when applicable.

What You Need to Do 👇

  1. Determine device MR safety classification (Safe, Unsafe, or Conditional)
  2. Develop test plan based on device type and classification
  3. Conduct required safety testing according to applicable standards
  4. Document test results and develop appropriate labeling
  5. Include comprehensive MRI Safety Information section in device labeling
  6. Create patient device card for implants and patient-worn devices
  7. Submit complete test reports in premarket submission
  8. Consider seeking FDA feedback through Q-submission process if needed
  9. Ensure labeling is readily accessible throughout device lifetime
  10. Maintain documentation of MR safety evaluation and testing

Key Considerations

Non-clinical testing

  • Testing for magnetically induced displacement force using ASTM F2052 for small devices
  • Testing for magnetically induced torque using ASTM F2213
  • Testing for RF-induced heating using ASTM F2182 for passive devices
  • Testing for gradient-induced vibration for active implantable devices
  • Testing for gradient-induced electrical potential for devices with electrodes
  • Testing for RF pulse rectification for active devices with electrodes
  • Testing for device malfunction in MR environment
  • Testing for image artifacts using ASTM F2119

Labelling

  • Must include MRI Safety Information section
  • Must label device as MR Safe, MR Unsafe, or MR Conditional with appropriate symbol
  • For MR Conditional devices, must specify conditions for safe use
  • Must include patient device card for implants and patient-worn devices
  • Must include information for both patients and healthcare providers
  • Must include image artifact information
  • Must include specific scan parameters and conditions when applicable

Safety

  • Must address magnetically induced displacement force
  • Must address magnetically induced torque
  • Must address RF-induced heating
  • Must address gradient-induced vibration
  • Must address gradient-induced electrical potential
  • Must address RF pulse rectification
  • Must address device malfunction risks
  • Must specify maximum allowed field strengths and exposure conditions

Other considerations

  • Must consider device size and configuration for worst-case testing scenarios
  • Must consider multiple MR field strengths (e.g., 1.5T, 3.0T)
  • Must consider different RF coil types and configurations
  • Must consider device location relative to MR bore
  • Must consider cooling periods between scans when applicable

Relevant Guidances 🔗

Related references and norms 📂

  • ASTM F2052: Standard Test Method for Measurement of Magnetically Induced Displacement Force on Medical Devices in the Magnetic Resonance Environment
  • ASTM F2119: Standard Test Method for Evaluation of MR Image Artifacts from Passive Implants
  • ASTM F2182: Standard Test Method for Measurement of Radio Frequency Induced Heating on or Near Passive Implants During Magnetic Resonance Imaging
  • ASTM F2213: Standard Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment
  • ASTM F2503: Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment
  • ISO/TS 10974: Assessment of the safety of magnetic resonance imaging for patients with an active implantable medical device
  • IEC 60601-2-33: Medical electrical equipment – Part 2-33: Particular requirements for the basic safety and essential performance of magnetic resonance equipment for medical diagnosis

Original guidance

  • Testing and Labeling of Medical Devices for Magnetic Resonance (MR) Environment Safety and Compatibility
  • HTML / PDF
  • Issue date: 2023-10-10
  • Last changed date: 2023-10-10
  • Status: FINAL
  • Official FDA topics: Radiation-Emitting Products, Medical Devices, Errors, and Problems, Labeling, Premarket, Safety - Issues
  • ReguVirta ID: 7f741a2bd682e52f2ee874669f9cc8f2
FDA guidance, Final
Radiation-Emitting Products Medical Devices Errors and Problems Labeling Premarket Safety - Issues
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