Conformal Compact Metasurface for Enhancing Performance of Brain Ultra-low-field Magnetic Resonance Imaging System

Ultra-low field magnetic resonance imaging (ULF-MRI) has an essential application in brain medical imaging diagnosis because of its light weight and low cost. However, ULF-MRI normally results in poor MR images and make it impossible to make an accurate medical diagnosis. In this work, a conformal compact hybrid metasurface structure, which is a double spiral metasurface (DSM) based on dielectric loading technique, designed to enhance the local signal-to-noise ratio (SNR) without increasing the strength of the static magnetic field of 0.1T MRI system. Results show that on the surface of a realistic multi-tissue voxel human brain phantom with using the conformal DSM, the field strength is enhanced by 2.9 times and the SNR is improved by 3.4 times. At the depth of 100mm from the surface, the SNR enhancement factor is still as high as 1.2. The reported conformal compact metasurface provide a local SNR enhancement method for brain ULF-MRI.