Aneurysm clips: magnetic quantification and magnetic resonance imaging safety. Technical note

Knowledge of the magnetic properties of cerebral aneurysm clips in patients undergoing magnetic resonance (MR) imaging is imperative. The authors quantified in electromagnetic units the magnetic properties of 13 different types of aneurysm clips by using a vibrating sample magnetometer. Their results showed that the magnetic moment of these clips ranged from 0.15 EMU/g to as high as 152.7 EMU/g. Based on these results and tests of the movement of the clips during MR imaging, they conclude that aneurysm clips with a magnetic moment less than 1 EMU/g may be safely used during MR imaging. The quantification of magnetic properties into electromagnetic units by using a vibrating sample magnetometer is a reliable method applicable to any testing field gradient. This method can be used as a standard to measure and label the magnetic properties of aneurysm clips.