RF shielding optimization for non planar surfaces in interventional MRI

Abstract

Magnetic Resonance Imaging (MRI) is a potential candidate for interventional cardiovascular procedures since it is ionizing radiation-free and thus safe for human use. However current devices su er from mechanical and electrical constraints and face with safety issues. Interventional MRI devices incorporate RF receiver antenna and long transmission lines for active visualization purpose are prone to RF induced heating. Therefore, alternative non-metallic transmission line technologies such as acousto-optic transmission line has been developed. The ultrasonic transducers used in acousto-optic transmission lines can couple with local E- eld changes during MRI scan and generate noise. This work aims to develop RF shielding coating methodology on non-planar surface to achieve the highest sensitivity for signal transmission by eliminating , noise generating factors. For this purpose, a compact housing design was constructed for the piezoelectric transducer that is coupled with an optical transmission line and a radio frequency solenoid coil. Also, the cross-talk between the ultrasound transducer and Magnetic Resonance Imaging scanner's electric eld aimed to be removed using di erent shielding materials. Shielding e ectiveness simulations were performed by using CST R software and measurements were performed within a gelled phantom as described in the ASTM F2182 standard. RF performances of the antennas and di erent shielding materials were measured using a vector network analyzer in terms of the scattering parameters. Network analyzer results demonstrated that MRI compatible copper powder-epoxy combination and conductive silver ink are feasible RF shielding materials because they show similar behavior compare to pure copper material.|Keywords : Interventional Cardiovascular MRI, RF Shielding