Contraindications for use

In general, patients with conductive (e.g. metallic) implants are contraindicated for MR scans. Some implantable devices have been labeled as MR Conditional under certain operating conditions. MR Safe implants will have the MR Safe symbol in their implant documentation.

When evaluating whether to proceed with MR scanning on patients with such implants, consult the implantable device’s labeling.

• MR Safe: For patients with implants that are labeled as MR Safe, consult the implantable device’s labeling.
• MR Conditional: For patients with implants that are labeled as MR Conditional, consult the implantable device’s labeling.
• MR Unsafe: Patients with implantable devices that are MR Unsafe are contraindicated.

If the level of MR compatibility is not known, then an implantable device should be considered MR Unsafe.

However, certain implantable medical devices have been cleared, approved and/or licensed by the Safe”. For such devices, the general contraindications as stated above may not be applicable in their entirety.

It is the responsibility of the implant manufacturer to declare an implant as “MR Conditional” or “MR Safe”, if appropriate, and to define the conditions (constraints) for safe MR scanning. The MR operator must be aware of any such conditions for MR scanning. It is the obligation of the MR operator to assure these conditions are strictly adhered to.

To obtain these specific conditions, the operator is advised to refer to the labelling of the implant or to contact the implant manufacturer. The MR manufacturer does not assume responsibility for the operation of the MR when scanning patients with any implantable medical device. Especially the MR manufacturer is not responsible for controlling technical parameters of the MR SYSTEM other than those defined by the normal operating mode or the first level controlled operating mode, the FPO (if available) and the data provided in the compatibility technical datasheet, such as spatial field gradient.

MR environment safety terminology

The MR Environment Safety Terminology is intended to help explain labeling matters for medical devices and other items that may be used in the MR environment to ensure the safe use of MR technology.

Terminology for defining the safety of items in the MR environment is provided in ASTM F2503 Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment. FDA recommended using the terminology MR Safe, MR Conditional, and MR Unsafe, defined in ASTM F2503 (FDA guidance document, “Establishing Safety and Compatibility of Passive Implants in the Magnetic Resonance (MR) Environment Document”).

Definitions

MR safe: or

An item that poses no known hazards in all MR imaging environments.

With this terminology, MR safe items are non-conducting, non-metallic, and non-magnetic items, such as a plastic Petri dish. An item may be determined to be MR safe by providing a scientifically based rationale rather than test data.

MR Conditional:

An item that has been demonstrated to pose no known hazards in specified MR environment with specified conditions of use. Field conditions that define the MR environment include static magnetic field strength, spatial gradient, time rate of change of the magnetic field (dB/dt), RF fields, and specific absorption rate (SAR).

Additional conditions, including specific configurations of the item (e.g., the routing of leads used for a neurostimulation system), may be required.

MR Unsafe:

An item that is known to pose hazards in all MR environments.

MR unsafe items include magnetic items such as a pair of ferromagnetic scissors.

ASTM standard F2503 also describes how MR Safe, MR Conditional and MR Unsafe device Icons are to be used for MR labeling of implants and devices. For details see MR safety labels.

When scanning patients with MR Conditional implants, check with GEHC to ensure your system has quadrature transmit.