RF Metasurface Based 'Add-Ons' for Boosting Signal-To-Noise Ratio of 1.5T MRI Scans.

Signal-to-noise ratio (SNR) is a crucial parameter for evaluating the performance of an MRI. Higher SNR results in better image resolution or shorter scanning time during MRI scans. One of the techniques for increasing the SNR is by using RF metasurfaces as ‘add-ons’, which could fit in the available free space (< 2 cm) in an MRI receive array. In this work, a7 mm thick metasurface, capable of providing a tenfold boost in the SNR of 1. 5 T MRI, has been proposed. The proposed metasurface constitutes of a dielectric pad sandwiched between two metallic layers. Each metallic layer comprises fourteen thin resonating wire strips, which localize and redistribute the RF magnetic field in the near-field region. Square copper patches have been introduced on these wire strips for concentrating the magnetic field in the region-of-interest (ROI). Full-wave simulations predict a high magnetic field enhancement of ~ seven times when the metasurface is placed as an ‘add-on’ on a human phantom during brain scan.