MR Safe (MR in a square)
The definition FDA’s guidance adapts from ASTM F2503:
“An item that poses no known hazards resulting from exposure to any MR environment. MR Safe items are composed of materials that are electrically nonconductive, nonmetallic, and nonmagnetic.”
ASTM F2503 (cited by FDA MR labelling guidance) · ASTM F2503, the practice FDA’s MR labelling guidance follows
What it means for you
Nothing in the item reacts to an MRI scanner. FDA’s guidance adds that small metal markers already rule it out, and that electrically active devices can never be MR Safe.
Whether a device is right for you is a question for your pharmacist, nurse or doctor.
- What it looks like
- The letters MR inside a square.
- Where you see it
- Plastic and ceramic devices, some catheters and positioning aids used around MRI scanners.
- Other names
- MRI safe; MR Safe
What it does not tell you
It does not cover other devices you have with you or in you. FDA’s guidance also says the old term “MR Compatible” is obsolete and should not be used — treat it as no answer.
Often confused with
An item with demonstrated safety in the MR environment within defined conditions including conditions for the static magnetic field, the time-varying gradient magnetic fields and the radiofrequency fields.
More symbols in “MR”
Sources
Taken from 3 publishers’ public documents. Each was fetched and read on the date shown:
- US Food and Drug Administration: Testing and Labeling Medical Devices for Safety in the Magnetic Resonance (MR) Environment — guidance issued 10 October 2023 — Defines MR Safe as “a medical device that poses no known hazards resulting from exposure to any MR environment … composed of materials that are electrically nonconductive, nonmetallic, and nonmagnetic”, adapted from ASTM F2503-20; says to include “the appropriate symbol from ASTM F2503”. Checked 2026-09-25.
- Boston Scientific: Symbols Glossary — Lists ASTM F2503-20 7.3.1 “MR Safe — An item that poses no known hazards resulting from exposure to any MR environment.” Checked 2026-09-25.
- NE Scientific: Master Symbol Glossary (CTF-100011 Rev 01) — Shows MR in a square for ASTM F2503 “Magnetic Resonance (MR) safe”. Checked 2026-09-25.
Plain-language parts are in our own words; quotations are the sources’ wording.