MR Safety Ratings, Tesla Levels, and MRI Suites

MRI environments require careful control of equipment based on MR safety ratings, Tesla field strength, and MRI room zones.  These factors determine what products can be safely used near the MRI system.


MR Safety Ratings

MRI-compatible equipment is classified under ASTM F2503:

MR Safe
Completely non-magnetic and non-conductive.  Safe for unrestricted use in the MRI room (Zone IV).

MR Conditional
Safe only under specific conditions, including maximum Tesla rating and use limitations.  Most MRI fire extinguishers are MR Conditional.

MR Unsafe
Contains ferromagnetic materials.  Not permitted in MRI environments due to projectile risk.


Tesla Ratings

The Tesla (T) rating defines the strength of the MRI magnetic field.

Common MRI systems:

•  1.5 Tesla
•  3 Tesla
•  7 Tesla
•  11.7 Tesla

 The Tesla rating applies to the MRI system, not the device.

MR Conditional equipment must be rated equal to or greater than the MRI field strength.  Example: A 3T MRI requires MR Conditional >= 3T.

Even equipment tested to 11.7 Tesla remains MR Conditional, not MR Safe. MRI testing is typically conducted near the magnet in the fringe field, not inside the bore where full field strength exists..


MRI Suite Zones

MRI facilities are divided into four zones:

Zone I – Public access
Zone II – Supervised access
Zone III – Restricted area (MRI control area)
Zone IV – MRI room

Only MR Safe or properly rated MR Conditional equipment is permitted in Zones III and IV.


Key Points

• MR Safe = No magnetic risk
• MR Conditional = Most MRI-rated equipment
• MR Unsafe = Not allowed near MRI
• Tesla rating defines the magnetic field strength of the MRI
• Equipment must be rated >= MRI Tesla level
• 11.7 Tesla-rated equipment is still MR Conditional

References

• ASTM F2503 – MRI Safety Labeling (Overview)
  https://medinstitute.com/services/mri-safety/mri-safety-information-and-labeling-astm-f2503/
  
  
• ASTM F2503 – Official Standard Listing
  https://www.astm.org/f2503-23e01.html
  
  
• NFPA 99 – Health Care Facilities Code
  https://www.nfpa.org/99
  
  
• FDA – MRI Safety Labeling Guidance
  https://www.fda.gov/media/74201/download
  
  
• MRI Safety Reference
  https://www.mrisafety.com

Disclaimer
This information is provided for general reference only and is not professional, engineering, or medical advice.  AmeraProducts, Inc. is a distributor and does not determine or certify MRI compatibility.  Product selection and use should be reviewed by qualified professionals, including the MRI system manufacturer and facility safety personnel.  Always verify current standards, manufacturer data, and site-specific requirements before installation.