Sub-Wavelength Imaging with BC-SRRs Metamaterial Lens for 1.5-T MRI

摘要

Magnetic resonance imaging (MRI) is the keystone technique to characterize the psychology and neurochemistry of human body. This imaging mechanism is advanced and with ample significances to detect the biological changes or diseases in human body. This work exploits the notable properties of compact/thin broadside coupled (BC) split ring resonator (SRR) metamaterial lens that can be use to enhance image quality of 1.5-T MRI systems. We analyzed two strongly coupled BC-SRR copper arrays attached on printed circuit board and loaded with parametric elements (capacitor and inductor). The significance of design is its compact thickness of 3.2 mm, its tunability at different working frequencies due to parametric elements and it places no restrictions on MR coil designing as proposed in previous work. The technique combining parametric elements, copper loops, and SRRs has not been used before for such lower working frequency. In addition, the designed lens persuades the radio frequency field's rotational symmetry around the its axis due to the uniformly induced currents along its arrays which in results, improves the mutual inductance between BC-SRR arrays, and finally restores the amplitude of magnetic field (B) at the considered area, e.g., phantom and enhances the image quality. The negative resonance at 63.8 MHz was achieved with relative negative permeability, mu (r) = -1.74 - j0.0063. Furthermore, image quality inside phantom was optimized in the presence or in the absence of BC-SRR lens by the analysis of thickness variations of MR coil of MRI system.