Monitoring, analysis, and correction of magnetic field fluctuations in echo planar imaging time series

Kasper, Lars, Bollmann, Saskia, Vannesjo, S. Johanna, Gross, Simon, Haeberlin, Maximilian, Dietrich, Benjamin E. and Pruessmann, Klaas P. (2015) Monitoring, analysis, and correction of magnetic field fluctuations in echo planar imaging time series. Magnetic Resonance in Medicine, 74 2: 396-409. doi:10.1002/mrm.25407


Author Kasper, Lars
Bollmann, Saskia
Vannesjo, S. Johanna
Gross, Simon
Haeberlin, Maximilian
Dietrich, Benjamin E.
Pruessmann, Klaas P.
Title Monitoring, analysis, and correction of magnetic field fluctuations in echo planar imaging time series
Journal name Magnetic Resonance in Medicine   Check publisher's open access policy
ISSN 1522-2594
0740-3194
Publication date 2015-08-01
Year available 2014
Sub-type Article (original research)
DOI 10.1002/mrm.25407
Open Access Status Not yet assessed
Volume 74
Issue 2
Start page 396
End page 409
Total pages 14
Place of publication Hoboken, NJ, United States
Publisher John Wiley & Sons
Language eng
Subject 2741 Radiology Nuclear Medicine and imaging
2700 Medicine
Abstract Purpose To assess the utility of concurrent magnetic field monitoring for observing and correcting for variations in k-space trajectories and global background fields that occur in single-shot echo planar imaging (EPI) time series as typically used in functional MRI (fMRI). Methods Field monitoring was performed using an array of NMR field probes operated concurrently with series of single-shot EPI acquisitions from a static phantom. The observed fluctuations in field evolution were analyzed in terms of their temporal and spatial behavior at the field level as well as at the level of reconstructed image series. The potential to correct for such fluctuations was assessed by accounting for them upon image reconstruction. An indication of the number and relative magnitude of underlying effects was obtained via principal component analysis. Results Trajectory and global field variations were found to induce substantial image fluctuations. Global field fluctuations induced standard deviations in image intensity up to 31%. Fluctuations in the trajectory induced ghosting artifacts with standard deviations up to 2%. Concurrent magnetic field monitoring reduced the fluctuations in the EPI time series to a maximum of 1.2%. Conclusion Concurrent magnetic field monitoring holds the potential to improve the net sensitivity of fMRI by reducing signal fluctuations unrelated to brain activity. Magn Reson Med 74:396-409, 2015.
Formatted abstract
Purpose: To assess the utility of concurrent magnetic field monitoring for observing and correcting for variations in k-space trajectories and global background fields that occur in single-shot echo planar imaging (EPI) time series as typically used in functional MRI (fMRI).

Methods: Field monitoring was performed using an array of NMR field probes operated concurrently with series of single-shot EPI acquisitions from a static phantom. The observed fluctuations in field evolution were analyzed in terms of their temporal and spatial behavior at the field level as well as at the level of reconstructed image series. The potential to correct for such fluctuations was assessed by accounting for them upon image reconstruction. An indication of the number and relative magnitude of underlying effects was obtained via principal component analysis.

Results: Trajectory and global field variations were found to induce substantial image fluctuations. Global field fluctuations induced standard deviations in image intensity up to 31%. Fluctuations in the trajectory induced ghosting artifacts with standard deviations up to 2%. Concurrent magnetic field monitoring reduced the fluctuations in the EPI time series to a maximum of 1.2%.

Conclusion: Concurrent magnetic field monitoring holds the potential to improve the net sensitivity of fMRI by reducing signal fluctuations unrelated to brain activity.
Keyword FMRI
Gradients
Noise
PCA
SFNR
Thermal drifts
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID 13756.1 PFFLM-NM
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Queensland Brain Institute Publications
Centre for Advanced Imaging Publications
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 12 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 12 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Fri, 19 May 2017, 01:00:34 EST by Web Cron on behalf of Learning and Research Services (UQ Library)