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Retrospective correction of physiological field fluctuations in high‐field brain MRI using concurrent field monitoring
Author(s) -
Vannesjo S. Johanna,
Wilm Bertram J.,
Duerst Yolanda,
Gross Simon,
Brunner David O.,
Dietrich Benjamin E.,
Schmid Thomas,
Barmet Christoph,
Pruessmann Klaas P.
Publication year - 2015
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.25303
Subject(s) - field (mathematics) , image resolution , image quality , breathing , computer science , field of view , magnetic resonance imaging , iterative reconstruction , motion field , computer vision , nuclear magnetic resonance , artificial intelligence , physics , motion (physics) , image (mathematics) , mathematics , radiology , medicine , pure mathematics , anatomy
Purpose Magnetic field fluctuations caused by subject motion, such as breathing or limb motion, can degrade image quality in brain MRI, especially at high field strengths. The purpose of this study was to investigate the feasibility of retrospectively correcting for such physiological field perturbations based on concurrent field monitoring. Theory and Methods High‐resolution T2*‐weighted gradient‐echo images of the brain were acquired at 7T with subjects performing different breathing and hand movement patterns. Field monitoring with a set of 19 F NMR probes distributed around the head was performed in two variants: concurrently with imaging or as a single field measurement per readout. The measured field fluctuations were then accounted for in the image reconstruction. Results Significant field fluctuations due to motion were observed in all subjects, resulting in severe artifacts in uncorrected images. The artifacts were largely removed by reconstruction based on field monitoring. Accounting for field perturbations up to the 1st spatial order was generally sufficient to recover good image quality. Conclusions It has been demonstrated that artifacts due to physiologically induced dynamic field perturbations can be greatly reduced by retrospective image correction based on field monitoring. The necessity to perform such correction is greatest at high fields and for field‐sensitive techniques such as T2*‐weighted imaging. Magn Reson Med 73:1833–1843, 2015. © 2014 Wiley Periodicals, Inc.