Homogeneous B0 coil design method for open-access ultra-low field magnetic resonance imaging: A simulation study

Magn Reson Imaging. 2024 Oct:112:128-135. doi: 10.1016/j.mri.2024.07.006. Epub 2024 Jul 8.

Abstract

A multimodal brain function measurement system integrating functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) is expected to be a tool that will provide new insights into neuroscience. To integrate fMRI and MEG, an ultra-low-field MRI (ULF-MRI) scanner that can generate a static magnetic field (B0) with an electromagnetic coil and turn off the B0 during MEG measurements is desirable. While electromagnetic B0 coil has the above advantages, it also has a trade-off between size and the broadness of the magnetic field homogeneity. In this study, we proposed a method for designing a B0 multi-stage circular coil arrangement that determines the number of coils required to maximize magnetic field homogeneity and minimize the total wiring length of the coils. The optimized multi-stage coil arrangement had an external shape of 600 mm in diameter and a maximum height of 600 mm, with an aperture of 600 mm in diameter and 300 mm in height. The magnetic field homogeneity was <100 ppm over a 210 mm diameter spherical volume (DSV). Compared to a previous two coil pairs arrangement with the same magnetic field homogeneity, the diameter was 1/1.9 times smaller, indicating that the newly designed B0 coil arrangement realized a smaller size and wider magnetic field homogeneity.

Keywords: Electromagnetic coil; Multi-objective optimization; Ultra-low-field MRI.

MeSH terms

  • Brain / diagnostic imaging
  • Computer Simulation*
  • Electromagnetic Fields
  • Equipment Design*
  • Humans
  • Magnetic Fields
  • Magnetic Resonance Imaging* / instrumentation
  • Magnetic Resonance Imaging* / methods
  • Magnetoencephalography / instrumentation
  • Magnetoencephalography / methods
  • Phantoms, Imaging