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MR Conditional is one of three standardized MRI safety labels. It means a medical device has demonstrated safety in the MR environment only within defined conditions, such as a stated static magnetic field strength, gradient limits and radiofrequency limits, and the label is valid only when every one of those conditions is met.
Short answer
An MR Conditional label is a promise with terms attached. The FDA defines MR Conditional as a device “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.” The British Institute of Radiology (BIR) puts the practical consequence plainly: the statement of demonstrated safety only applies when all of the stated MR conditions are met. The label alone is therefore never the whole answer; the conditions listed with it are.
Definition and scope
The three terms, MR Safe, MR Conditional and MR Unsafe, come from the ASTM F2503 standard for marking medical devices and other items for safety in the MR environment. The FDA guidance Testing and Labeling Medical Devices for Safety in the Magnetic Resonance (MR) Environment (issued October 10, 2023, nonbinding) recommends labeling consistent with ASTM F2503 and including the standard’s symbol and/or the corresponding term. Color symbols are recommended, though black-and-white may be used.
The BIR’s 2026 advice note reports that ASTM F2503-26 was published in 2026 with small changes to improve the wording of the definitions, and that the intention behind each definition is unchanged. In the BIR’s updated wording, MR Conditional means having demonstrated safety in the MR Environment within defined conditions.
The “MR environment” itself is the volume around the scanner where a hazard may arise. The BIR describes it as the combination of the B0 hazard area (the 0.9 mT fringe field, often called the 9 gauss line) and the Faraday shielded volume, which is the RF cabin. For how those areas are zoned and who may enter them, see the guide to MRI safety zones and MR personnel levels.
The hazards the FDA guidance addresses are magnetically induced displacement force and torque, RF-induced heating, gradient-induced vibration, device malfunction and image artifact. An MR Conditional claim rests on testing evidence for those hazards within the stated limits. The BIR links this to ISO 14971, where safety means freedom from unacceptable risk: manufacturers gather MR safety test evidence showing acceptable residual risk within the conditions they state.
How an MR Conditional label is read in practice
The BIR describes a three-step reading of any MR Conditional item:
- The item is labelled MR Conditional.
- Establish what all of its conditions are.
- Establish whether all of those conditions can be met.
Step three is where the label stops being a yes or no. The decision for an individual device in a specific clinical procedure sits outside ISO 14971 and needs a qualified medical practitioner, according to the BIR; the MHRA and the American College of Radiology publish guidance for local procedures.
What the conditions can cover
The FDA recommends that the labeling of a device expected to enter the scanner bore include the MR Conditional symbol and/or term and the nominal permitted static magnetic field strength in tesla. Then, when needed for the specific device, it can add the following parameters.
| Condition on the label | Unit or form the FDA lists |
|---|---|
| Static magnetic field strength (B0) | Tesla (T) |
| Nucleus imaged | Hydrogen (1H) is assumed if none is listed |
| Scanner type and B0 orientation | For example, cylindrical-bore |
| Maximum spatial field gradient | T/m and G/cm |
| Maximum gradient slew rate | T/m/s, per axis |
| RF excitation, RF transmit coil and RF receive coil type | Stated by type |
| Maximum whole-body and/or head SAR | W/kg, with the operating mode (Normal Operating Mode or First Level Controlled Operating Mode) |
| Maximum B1+rms | mT |
| Scan duration and wait time | Stated limits |
| MR exam exclusion zones and patient position | Stated limits |
| Image artifact information, and instructions before and after the exam | Informational |
One sentence in the FDA guidance changes how a label is read: if a parameter is not listed, no modifications of that parameter are needed for the safe scanning of a patient. An unlisted parameter is therefore not something to improvise a limit for.
MR Conditional compared with MR Safe, MR Unsafe and not evaluated
| Label | What the FDA and BIR say it means |
|---|---|
| MR Safe | Poses no known hazards from exposure to any MR environment. Composed of materials that are electrically nonconductive, nonmetallic and nonmagnetic. |
| MR Conditional | Demonstrated safety in the MR environment within defined conditions for the static, gradient and RF fields. Valid only when all conditions are met. |
| MR Unsafe | Poses unacceptable risks to the patient, medical staff or other persons in the MR environment. For non-implanted devices the icon should appear directly on the device where possible, and labeling may also indicate a projectile hazard. |
| Safety in MRI not evaluated | A separate statement the FDA describes for some passive devices: the device has not been evaluated for safety in the MR environment and has not been tested for heating or unwanted movement. |
Where it matters for labs, clinics and supply decisions
Three points from the FDA and BIR material bear directly on equipment and supply records in an imaging setting.
- Field strength is part of the label. The FDA states that a device that is MR Conditional in a 1.5 T system may be unsafe in higher or lower field systems, so the tesla value on the label has to be compared with the scanner in use.
- Conditions are per model. The FDA notes that the conditions may not be the same for all models of a device, so a condition set cannot be carried from one model to another.
- Combined devices. The FDA lists, as essential information a label may carry, that a patient with other MR Conditional devices can be scanned only if all conditions for each device are met.
For a broader view of what an imaging area stocks and documents, see the radiology and imaging center supply checklist. For the equipment itself, see what an MRI scanner is, and for a widely known implanted example see what a pacemaker is. Regulatory background on how devices are defined is in what a medical device is.
Common misunderstandings
“MR Conditional means MRI-safe.”
It does not. MR Safe is a separate label with a stricter material requirement. MR Conditional means safe within the stated conditions and only those.
“Electrically active devices can be MR Safe.”
The FDA states that electrically active medical devices should be designated either MR Conditional or MR Unsafe, but not MR Safe, because they contain electrically conductive components.
“MR Safe items cannot affect the image.”
The BIR notes that MR Safe items may still cause MR image artifacts, and gives an alcohol wipe as an example. MR Safe describes hazard, not image quality.
“A 1.5 T label covers every scanner.”
See the field strength point above: the FDA says a device that is MR Conditional at 1.5 T may be unsafe in higher or lower field systems.
“The wording changed in 2026, so older labels are invalid.”
The BIR describes the ASTM F2503-26 changes as small wording improvements to the definitions, with the intentions behind each unchanged. The three terms and their meaning are the same.
Frequently asked questions
What does MR Conditional mean?
It means a device has demonstrated safety in the MR environment within defined conditions covering the static magnetic field, the time-varying gradient fields and the radiofrequency fields. The safety statement applies only when all of those conditions are met.
Which standard defines the term?
ASTM F2503. The FDA guidance recommends labeling consistent with it, and the BIR reports that the 2026 edition is F2503-26.
Is MR Conditional the same as MR Safe?
No. MR Safe applies to items made entirely of electrically nonconductive, nonmetallic and nonmagnetic materials that pose no known hazard in any MR environment. MR Conditional carries conditions.
Where is the list of conditions found?
In the device labeling. The FDA recommends that labeling for patients and for healthcare providers carry the symbol or term, the permitted static field strength and, when needed, the other parameters listed above. Whether a specific device can be scanned in a specific procedure is a decision for a qualified medical practitioner and the local MR safety procedure.
Sources
- U.S. Food and Drug Administration, Testing and Labeling Medical Devices for Safety in the Magnetic Resonance (MR) Environment, guidance issued October 10, 2023; checked October 29, 2026.
- British Institute of Radiology, MR Safety Advice 2026: Update to the MR safety labelling standard; checked October 29, 2026.
- ASTM International, ASTM F2503-26, standard practice for marking medical devices and other items for safety in the MR environment, as cited by the BIR; listing checked October 29, 2026.
