Aneurysm Clips
Some clips are a contraindication for the MR environment, whereas others are deemed safe for patients or individuals exposed to MR systems operating at 1.5 T or less. For these MR systems, positive documented evidence must be obtained that the clip is non- or weakly ferromagnetic, before any person with a clip is exposed to the MR environment. Persons with aneurysm clips in the head are in particular danger, because fibrosis (thickening and scarring of the tissue around the implant, fixing it in place) may not always occur.
Further reading on this topic:
Books: MHRA Guidelines p55
Online: J Magn Reson Imaging 2002;16:485-496