Significance and Use
5.1 This test method is one of those required to determine if the presence of a medical device may cause injury to individuals during an MR examination and in the MR environment. Other safety issues which should be addressed include but may not be limited to magnetically induced torque (see Test Method ) and RF heating (see Test Method ). The terms and icons in Practice should be used to mark the device for safety in the magnetic resonance environment.
5.2 If the device deflects less than 45°, then the magnetically induced deflection force is less than the force on the device due to gravity (its weight). For this condition, it is assumed that any risk imposed by the application of the magnetically induced force is no greater than any risk imposed by normal daily activity in the Earth's gravitational field. This statement does not constitute an acceptance criterion, however it is provided for a conservative reference point. It is possible that a greater magnetically induced deflection force can be acceptable and would not harm a patient. For forces greater than gravity the location of the implant and means of fixation must be considered. Magnetically induced deflection forces greater than the force of gravity may be acceptable when they can be justified for the specific case.
5.3 A deflection of less than 45° at the location of the maximum spatial gradient of the static magnetic field in one MR system does not preclude a deflection exceeding 45° in a system with a higher field strength or larger static field spatial gradients.
5.4 This test method alone is not sufficient for determining if a device is safe in the MR environment.
1.1 This test method covers the measurement of the magnetically induced displacement force produced by static magnetic field gradients on medical devices and the comparison of that force to the weight of the medical device.
1.2 This test method does not address other possible safety issues which include but are not limited to issues of magnetically induced torque, RF heating, induced heating, acoustic noise, interaction among devices, and the functionality of the device and the MR system.
1.3 This test method is intended for devices that can be suspended from a string. Devices which cannot be suspended from a string are not covered by this test method. The weight of the string from which the device is suspended during the test must be less than 1 % of the weight of the tested device.
1.4 This test method shall be carried out in a horizontal bore MR system with a static magnetic filed oriented horizontally and parallel to the MR system bore.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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 requirements prior to use.