Summary: RF Safe DBS Electrode Experiment: Using Floating Current Trap
Haydar Celik, Volkan Acikel, and Ergin Atalar
Electrical Engineering, Bilkent University, Ankara, Turkey
MRI has been used for imaging deep brain stimulator (DBS) lead and fMRI studies (1-2), however, these leads can be dangerous
under RF field (2). Both postoperative imaging of the electrodes and fMRI studies will pave the way of better understanding of the
placements of the electrodes and functionality of the DBS systems, but, field produced by RF coils induces current on wires and
causes temperature increase at the tip of the wire and causes safety problems (3,4). Therefore, this current should be eliminated for
safe MR operations.
Seeber et.al. introduced floating shield current trap for preventing currents on the coil connection cables (5). Purpose of this study is to
develop a system that allows fMRI operation safely while activating the brain using DBS leads. We planed to achieve this goal by
using a floating current trap (FCT) that blocks the current on a commercially available DBS lead without any modification on the lead
In this study, by using the same approach, the FCT is used to eliminate the induced RF current on DBS electrodes.
In order to achieve better suppression of the current, high quality factor FCT was designed (Figure 1a-b). Length of the FCT is 10 cm
and diameter is 3 cm. Air is used as dielectric material instead of Teflon, as a result we achieved 1180 ohms impedance and loaded
quality factor of 524.
The safety index (3,4) was measured using phantom (a gel filled spherical bottle) experiments. Electrode and two temperature sensors
were placed into the gel. The bottle was placed inside the 8-Channel brain array coil. 1.5 T MR scanner (Signa; Excite, GE medical