An artificial dielectric slab for ultra high-field MRI : Proof of concept, Vsevolod Vorobyev, Alena Shchelokova, Irena Zivkovic, Alexey Slobozhanyuk, Juan D.Baena, Juan P.del Risco, Redha Abdeddaim, Andrew Webb, Stanislav Glybovski ; Journal of Magnetic Resonance, Volume 320, November 2020, 106835
High-permittivity dielectric pads, i.e., thin, flexible slabs, usually consisting of mixed ceramic powders and liquids, have been previously shown to increase the magnetic field at high and ultra high-fields in regions of low efficiency of transmit coils, thus improving the homogeneity of images. However, their material parameters can change with time, and some materials they contain are bio incompatible. This article presents an alternative approach replacing ceramic mixtures with a low-cost and stable artificial dielectric slab. The latter comprises a stack of capacitive grids realized using multiple printed-circuit boards. Results in this article show that the proposed artificial dielectric structure can obtain the same increase in the local transmit radiofrequency magnetic field distribution in a head phantom at 7 T as the conventional dielectric pad.
Keywords : Ultra high-field MRI, 7 T, inhomogeneity, Dielectric pad, Artificial dielectric, Metamaterial, Radiofrequency coil
Partners : ITMO University, Aix Marseille University, CNRS, Centrale Marseille
Others Partners : Leiden University Medical Center, Universidad Nacional de Colombia & School of Exact Sciences and Engineering, Universidad Sergio Arboleda, Bogota
Available online : 24 September 2020.