This article reviews recent developments in designing and testing new types of materials which can be: (i) placed around the body for in vivo imaging, (ii) be integrated into a conventional RF coil, or (iii) form the resonator itself. These materials can improve the quality of MRI scans for both in vivo and magnetic resonance microscopy applications. The methodological section covers the basic operation and design of two different types of materials, namely high permittivity materials constructed from ceramics and artificial dielectrics/metasurfaces formed by coupled conductive subunits, either in air or surrounded by dielectric material. Applications of high permittivity materials and metasurfaces placed next to the body to neuroimaging and extremity imaging at 7 T, body and neuroimaging at 3 T, and extremity imaging at 1.5 T are shown. Results using ceramic resonators for both high field in vivo imaging and magnetic resonance microscopy are also shown. The development of new materials to improve MR image quality remains an active area of research, but has not yet found significant use in clinical applications. This is mainly due to practical issues such as specific absorption rate modelling, accurate and reproducible placement, and acceptable size/weight of such materials. The most successful area has been simple “dielectric pads” for neuroimaging at 7 T which were initially developed somewhat as a stop-gap while parallel transmit technology was being developed, but have continued to be used at many sites. Some of these issues can potentially be overcome using much lighter metasurfaces and artificial dielectrics, which are just beginning to be assessed.
|Number of pages||20|
|Journal||Magnetic Resonance Materials in Physics, Biology and Medicine|
|Publication status||Published - Dec 2022|
Bibliographical noteFunding Information:
This project was funded by the European Research Council Advanced grant 670629 NOMA MRI (AW, IZ, RS). Alena Shchelokova acknowledges support of Russian Science Foundation (Grant No. 21-79-30038).
- Artificial dielectrics
- High permittivity materials
- Transmit efficiency
- Magnetic Resonance Spectroscopy
- Magnetic Resonance Imaging/methods
- Phantoms, Imaging