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    ASTM F2503

    Standard practice for marking medical devices and other items for safety in the magnetic resonance environment.

    Reviewed by Christian Espinosa, Founder, Blue Goat CyberLast reviewed May 5, 2026

    Definition

    ASTM F2503 defines the MR Safe (green square), MR Conditional (yellow triangle), and MR Unsafe (red circle) markings used on devices and accessories in MR-equipped facilities.
    What the regulation says
    ASTM F2503, Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance (MR) Environment, provides a standardized system for labeling medical devices and other items to indicate their compatibility with the MR environment. This standard is recognized by regulatory bodies such as the FDA in their guidance documents concerning MR compatibility of medical devices.

    What this means in practice

    Required labeling element for any device that may enter or be used near MR scanners, including implants, monitoring equipment, and accessories.

    Examples

    • A pacemaker is labeled 'MR Conditional' with specific conditions, including a maximum static magnetic field strength of 1.5 Tesla and a maximum spatial gradient field of 500 Gauss/cm.
    • A patient undergoing an MRI has a metallic joint implant, which is correctly identified as 'MR Conditional' based on its labeling, and the imaging protocol is adjusted accordingly.
    • A hospital purchases new infusion pumps that are clearly marked 'MR Safe,' allowing them to be used directly within the MRI scanner room without concern for magnetic interference.
    Common pitfalls
    • •Misinterpreting 'MR Conditional' to mean a device is safe under all MR conditions, without considering the specific parameters and warnings outlined in the device's labeling.
    • •Failing to properly train personnel on the meaning of MR safety labels and the associated risks.
    • •Applying incorrect or unverified MR safety labels to devices, leading to potential harm to patients or damage to equipment.
    • •Not accounting for changes in a device's MR compatibility after repair or modification.

    Frequently asked questions

    The standard defines three primary classifications: MR Safe (green square), MR Conditional (yellow triangle), and MR Unsafe (red circle). These icons visually communicate the device's compatibility with magnetic resonance environments.
    Grouped by theme

    Primary references

    3 sources
    Link health: 3 verified· last checked 2026-06-20
    ASTM·1AAMI·1FDA·1
    1. 1
      ASTM F2503
      Verified
      ASTMastm.org
    2. 2
      AAMI Standards
      Verified
      AAMIaami.org
    3. 3
      FDA Recognized Consensus Standards
      Verified
      FDAaccessdata.fda.gov

    Inline markers like [1] jump to the matching reference above.