Comparison of positioning methods of a ferromagnetic sphere for magnetic steering using 3 T MRI.

Magnetic steering of an untethered ferromagnetic device in a living body has many advantages in the clinical fields. In this paper, the positioning and tracking methods of a ferromagnetic sphere have been compared with magnetic resonance phantom images obtained with three different imaging sequences, spin echo, gradient echo, and selected positive contrast sequences. The position of the ferromagnetic sphere has been calculated from the MRI images which have susceptibility artifacts caused by the magnetic sphere. We have compared the positioning errors among the magnetic sphere images.