Metamaterial Magnetic Sheet at 3.7-T MRI for Animal Imaging

Abstract

Animal models have been utilized for many decades to examine human diseases and symptoms via magnetic resonance imaging (MRI) techniques. To avoid the fatal effects of the strong static magnetic field (B0) when imaging the mouse brain at higher Tesla values in MRI, i.e., 7-T, we propose a compact metamaterial magnetic sheet which can improve the image resolution for simulation of the mouse brain even at lower Tesla values in MRI systems. The magnetic sheet operates at 3.7-T MRI working frequency and provides a passband within its interfaces to restore the formation of scattering of an evanescent radio-frequency (RF) field radiating from the MRI gradient coils towards the sheet. We show in the optimized simulated test bed setup that the magnetic sheet localizes and adjusts the response of the evanescent RF field and improves the transient transverse magnetic field B1 and signal-to-noise ratio at the designated region of interest, i.e., mouse brain (Mb), where B1 at the mouse brain is the response of the static magnetic field B0 generated by the magnetic resonance gradient coils. The unique concept proposed here is that negative permeability (−μ) controls the metamaterial magnetic sheet to improve image resolution inside the human brain without increasing B0 intensity at the brain, in order to avoid thermal heating of the brain tissues.