1. Scope

1.1 This test method covers measurement of radio frequency (RF) induced heating on or near a passive medical implant and its surroundings during magnetic resonance imaging (MRI).

1.2 This test method is one of those required to determine if the presence of a passive implant may cause injury to the patient with the implant during an MR procedure. Other safety issues that should be addressed include magnetically induced displacement force and torque.

1.3 The amount of RF-induced temperature rise for a given specific absorption rate (SAR) will depend on the RF frequency, which is dependent on the static magnetic field strength of the MR system. Because of possible additional heating, particularly when implant dimensions approaches or exceeds onequarter of the wavelength of the RF field inside the phantom, conclusions from measurements made at one static magnetic field strength do not apply to other field strengths and frequencies. While the focus in this test method is on 1.5 T or 3 Tesla cylindrical bore MR systems, the RF-induced temperature rise for an implant in open MR systems can be evaluated by suitable modification of the method described herein.

1.4 This test method assumes that testing is done on devices that will be entirely inside the body. For other implantation conditions (for example, external fixation devices, percutaneous needles, catheters or tethered devices such as ablation probes), modifications of this test method are necessary.

1.5 This test method applies to whole body magnetic resonance equipment, as defined in section 2.2.103 of the IEC Standard 60601-2-33, Ed. 2.0, with a whole body RF transmit coil as defined in section 2.2.100. The RF coil is assumed to have quadrature excitation.

1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

F2052 Test Method for Measurement of Magnetically Induced Displacement Force on Medical Devices in the Magnetic Resonance Environment

F2119 Test Method for Evaluation of MR Image Artifacts from Passive Implants

F2213 Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment

F2503 Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment

IEC Standard

NEMA Standard

Keywords

implant; MRI (magnetic resonance imaging); MR safety; RF (radio frequency) heating; Whole body magnetic resonance; Passive implants; RF-induced temperature rise; MRI (magnetic resonance imaging); RF (radio frequency) receivers; Specific absorption rate (SAR);

ICS Code

ICS Number Code 11.040.40 (Implants for surgery, prothetics and orthotics)

DOI: 10.1520/F2182-09

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