Motion and image artifacts of various intracranial aneurysm clips in a magnetic field

Deflection angles of 36 types of Sugita intracranial aneurysm clips (Elgiloy), 2 types of Yasargil clips (Phynox), a Kirschner chip (SUS316) and a silver clip were examined by suspending each in a 1.5-tesla MRI (TOSHIBA MRT-200/FXII). Image artifacts of 5 types of intracranial aneurysm clips were also studied quantitatively with respect to their ratio of artifact/actual clip size using a spin-echo sequence with T1-weighted (Time of repetition (TR) = 500 ms, Time of echo (TE) = 20 ms) and T2-weighted (TR = 2000 ms, TE = 80 ms) images. All the Sugita clips from mini type to long type showed a deflection angle of less than 1.0 degree, the Yasargil clips less than 2.0 degrees, the Kirschner chip less than 6.0 degrees, and the silver chip did not move at all. Both brands of clips are therefore suitable for intracranial applications. The artifact size was directly proportional to the clip size and weight, though the ratio of artifact/actual width tended to decrease proportionately as the actual size and weight increased. The ratio of the width seemed slightly bigger than that of the length, but the difference did not reach statistical significance. There was no significant difference in the ratio of image artifacts/clip size between T1- and T2-weighted images.