An artificial dielectric slab for ultra high-field MRI: Proof of concept

• Published in: Journal of magnetic resonance (1997) Vol. 320; p. 106835
• Main Authors: Vorobyev, Vsevolod, Shchelokova, Alena, Zivkovic, Irena, Slobozhanyuk, Alexey, Baena, Juan D., del Risco, Juan P., Abdeddaim, Redha, Webb, Andrew, Glybovski, Stanislav
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-11-2020; Elsevier
• Subjects: 7 T; [formula omitted] inhomogeneity; Artificial dielectric; Dielectric pad; Engineering Sciences; Metamaterial; Radiofrequency coil; Ultra high-field MRI; Ultra high-field MRI; Artificial dielectric; 7 T; Radiofrequency coil; Dielectric pad; Metamaterial; B1 inhomogeneity; inhomogeneity
• ISSN: 1090-7807; 1096-0856
• DOI: 10.1016/j.jmr.2020.106835

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•First ever successful application of artificial dielectric in MRI.•Transmit field can be increased in the area of the parietal lobes at 7 T.•The field increase of artificial dielectric slab is similar to dielectric pad.•Artificial dielectric slab was designed using cheap and available FR4 substrates.•The artificial dielectric was designed to be non-resonant and almost non-dispersive.
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.