This resource is designed to introduce the reader to the field of NMR/MRI at very low magnetic fields, from milli-Tesla to micro-Tesla, the ultra-low field (ULF) regime, and is focused on applications to imaging the human brain, and hardware methods primarily based upon pre-polarization methods and SQUID-based detection. Its goal is to provide insight and tools to better understand what applications are best served by ULF NMR/MRI approaches. A discussion of the hardware challenges, such as shielding, operation of SQUID sensors in a dynamic field environment, and pulsed magnetic field generation are presented. It also provides a framework of understanding the approaches to estimation and mitigation of low signal-to-noise and long imaging time, which are the main challenges, and special attention is paid to the combination of MEG and ULF MRI, and the benefits and challenges presented by trying to accomplish both with the same hardware.
Robert Kraus, author Samitaur Medical Technologies
Michelle Espy, author Los Alamos National Laboratory
Per Magnelind, author Los Alamos National Laboratory
Petr Volegov, author Los Alamos National Laboratory
date: 08 May 2021