電気・電子システムジャーナル

0 μ Magnetic Polarizer for 1.5-T MRI

Abstract

Hassan Ali, Erik Forsberg and Hu Jun

Study of human pathologies and acquisition of anatomical images without any surgical intervention inside human body is possible because of magnetic resonance imaging (MRI). This work exploits the notable properties of zero permeability (0 μ) split ring resonators (SRR) metamaterial (MM) magnetic polarizer which could distort, control and reject uniform RF (radio frequency) magnetic field for 1.5-T MRI systems. Unique polarizer was proposed to etch on PCB (printed circuit board) slabs for compact thickness of 5 mm only. In addition, polarizer was loaded with novel combination of parametric elements (capacitors, inductors) which could made the structure tunable to achieve resonance at different working frequencies. We achieved the value of relative permeability, μ_r=0.02+j0.1 for 1.5-T MRI systems at 63.85 MHz. Furthermore polarizer, when used with MRI scanner at optimized position, uniformly redistributed and enhanced the magnetic field while lowered specific absorption ratio (SAR), induced electric field, power dissipation, and locally improved SNR (signal to noise ratio) at the scanned region of phantom {real case was human body}. The polarizer minimized the damaging effects of RF energy absorption in human tissue and prevented them from heating.