title: Diffusion MRI with concurrent magnetic field monitoring.
abstract: OBJECTIVE
  Diffusion MRI is compromised by unknown field perturbation during image encoding. The purpose of this study was to address this problem using the recently described approach of concurrent magnetic field monitoring.
  
  
  METHODS
  Magnetic field dynamics were monitored during the echo planar imaging readout of a common diffusion-weighted MRI sequence using an integrated magnetic field camera setup. The image encoding including encoding changes over the duration of entire scans were quantified and analyzed. Field perturbations were corrected by accounting for them in generalized image reconstruction. The impact on image quality along with geometrical congruence among different diffusion-weighted images was assessed both qualitatively and quantitatively.
  
  
  RESULTS
  The most significant field perturbations were found to be related to higher-order eddy currents from diffusion-weighting gradients and B0 field drift as well as gradual changes of short-term eddy current behavior and mechanical oscillations during the scan. All artifacts relating to dynamic field perturbations were eliminated by incorporating the measured encoding in image reconstruction.
  
  
  CONCLUSIONS
  Concurrent field monitoring combined with generalized reconstruction enhances depiction fidelity in diffusion imaging. In addition to artifact reduction, it improves geometric congruence and thus facilitates image combination for quantitative diffusion analysis.
authors.affiliation: Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland.
authors.forename: Bertram J
authors.initials: BJ
authors.lastname: Wilm
authors.affiliation: Laboratory for Social and Neural Systems Research, University of Zurich, Switzerland.
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Nagy
authors.affiliation: Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland.|Skope Magnetic Resonance Technologies LCC, Zurich, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Barmet
authors.affiliation: Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland.
authors.forename: S Johanna
authors.initials: SJ
authors.lastname: Vannesjo
authors.affiliation: Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland.|Translational Neuromodeling Unit, Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland.
authors.forename: Lars
authors.initials: L
authors.lastname: Kasper
authors.affiliation: Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland.
authors.forename: Max
authors.initials: M
authors.lastname: Haeberlin
authors.affiliation: Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland.
authors.forename: Simon
authors.initials: S
authors.lastname: Gross
authors.affiliation: Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland.
authors.forename: Benjamin E
authors.initials: BE
authors.lastname: Dietrich
authors.affiliation: Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland.
authors.forename: David O
authors.initials: DO
authors.lastname: Brunner
authors.affiliation: Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmid
authors.affiliation: Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Switzerland.
authors.forename: Klaas P
authors.initials: KP
authors.lastname: Pruessmann
mesh_terms: D000328:Adult; D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D060526:Magnetic Fields; D019047:Phantoms, Imaging; D013696:Temperature; D055815:Young Adult
keywords: DTI; DWI; artifact correction; diffusion; distortion correction; field monitoring