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Criteria for Significant Risk Investigations of Magnetic Resonance Diagnostic Devices

This guidance outlines the criteria for determining when investigations of Magnetic Resonance Diagnostic Devices (MRD) are considered significant risk, requiring FDA approval of an Investigation Device Exemption (IDE). It applies to class II devices under 21 CFR 892.1000, including Magnetic Resonance Imaging Systems and Magnetic Resonance Spectroscopic Systems.

  1. Assess planned operating conditions against the specified limits for magnetic field, SAR, gradient fields, and sound pressure
  2. If any operating condition exceeds the specified limits, prepare for IDE submission
  3. Implement appropriate safety controls and monitoring for all specified parameters
  4. Ensure compliance with IRB and informed consent requirements
  5. Contact FDA for clarification on local SAR criteria if needed
  6. Review complete risk assessment beyond just operating conditions
  7. Maintain documentation of operating conditions and safety measures
  8. Establish protocols for monitoring and maintaining operating conditions within specified limits

Key Considerations

Clinical testing

  • Studies requiring IDE approval must comply with institutional review boards (21 CFR Part 56) and informed consent (21 CFR Part 50)
  • After substantial equivalence determination, clinical studies conducted within approved indications are exempt from IDE requirements

Safety

  • Main static magnetic field limits:
    • 8 tesla for adults, children, and infants > 1 month

    • 4 tesla for neonates (≤ 1 month)

  • Specific Absorption Rate (SAR) limits:
    • Whole body: > 4 W/kg averaged over 15 minutes
    • Head: > 3.2 W/kg averaged over 10 minutes
  • Gradient fields: Any rate of change causing severe discomfort or painful nerve stimulation
  • Sound pressure limits:
    • Peak unweighted level > 140 dB
    • A-weighted RMS level > 99 dBA with hearing protection

Other considerations

  • 21 CFR 892.1000: Magnetic Resonance Diagnostic Device
  • 21 CFR Part 812: Investigational Device Exemptions
  • 21 CFR Part 56: Institutional Review Boards
  • 21 CFR Part 50: Protection of Human Subjects

Original guidance

  • Criteria for Significant Risk Investigations of Magnetic Resonance Diagnostic Devices
  • HTML / PDF
  • Issue date: 2014-06-19
  • Last changed date: 2020-03-24
  • Status: FINAL
  • Official FDA topics: Medical Devices, Premarket
  • ReguVirta summary file ID: 6a83d7fcb51ed50470c894bdd008d936
This post is licensed under CC BY 4.0 by the author.