Measuring Motion-Induced B0-Fluctuations in the Brain Using Field Probes

Mads Andersen, Lars G. Hanson, Kristoffer Hougaard Madsen, Joep Wezel, Vincent Boer, Tijl van der Velden, Matthias J.P. van Osch, Dennis Klomp, Andrew G. Webb, Maarten J. Versluis

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Abstract

Purpose: Fluctuations of the background magnetic field (B0) due to body and breathing motion can lead to significant artifacts in brain imaging at ultrahigh field. Corrections based on real-time sensing using external field probes show great potential. This study evaluates different aspects of field interpolation from these probes into the brain which is implicit in such methods. Measurements and simulations were performed to quantify how well B0-fluctuations in the brain due to body and breathing motion are reflected in external field probe measurements. Methods: Field probe measurements were compared with scanner acquired B0-maps from experiments with breathing and shoulder movements. A realistic simulation of B0-fluctuations caused by breathing was performed, and used for testing different sets of field probe positions. Results: The B0-fluctuations were well reflected in the field probe measurements in the shoulder experiments, while the breathing experiments showed only moderate correspondence. The simulations showed the importance of the probe positions, and that performing full 3rd order corrections based on 16 field probes is not recommended. Conclusion: Methods for quantitative assessment of the field interpolation problem were developed and demonstrated. Field corrections based on external field measurements show great potential, although potential pitfalls were identified.
Original languageEnglish
JournalMagnetic Resonance in Medicine
Volume75
Issue number5
Pages (from-to)2020-2030
ISSN0740-3194
DOIs
Publication statusPublished - 2016

Keywords

  • Field fluctuations
  • Motion
  • NMR field probes
  • 7 Tesla
  • Dynamic shimming
  • Field mapping

Cite this

Andersen, M., Hanson, L. G., Madsen, K. H., Wezel, J., Boer, V., van der Velden, T., van Osch, M. J. P., Klomp, D., Webb, A. G., & Versluis, M. J. (2016). Measuring Motion-Induced B0-Fluctuations in the Brain Using Field Probes. Magnetic Resonance in Medicine, 75(5), 2020-2030. https://doi.org/10.1002/mrm.25802