Online motion correction for diffusion-weighted segmented-EPI and FLASH imaging

K. S. Weih, W. Driesel, M. Von Mengershausen, D. G. Norris*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

15 Citations (Scopus)


This paper explores the application of online motion correction using navigator echoes to the segmented-EPI and FLASH techniques. In segmented EPI this has the advantage over post-acquisition correction that the position in k-space of each segment is no longer subject to arbitrary shifts caused by rotation. In diffusion-weighted FLASH it has the advantage that the full magnetisation can be utilised in comparison to other methods of eliminating the sensitivity to bulk motion, in which the sensitivity is halved. Healthy subjects were investigated on a 3 T whole-body system in which the hardware has been modified so that navigator echoes can be recorded on a personal computer which generates the necessary magnetic field gradient correction pulses and shifts in the Larmor frequency within 800 μs. ECG triggering was used to avoid the period of non-rigid-body brain motion. Two orthogonal navigator echoes were employed. For segmented EPI it was found essential to minimise the T2* weighting of the navigator echoes to about 10 ms to obtain reliable results. High quality images were obtained for both methods examined. Online motion correction brings direct benefits to both the diffusion-weighted segmented-EPI and FLASH techniques.

Original languageEnglish
Pages (from-to)277-283
Number of pages7
JournalMagnetic resonance materials in physics, biology and medicine
Issue number6
Publication statusPublished - May 2004
Externally publishedYes


  • Diffusion magnetic resonance imaging
  • Echo-planar imaging
  • Navigator echoes
  • Online motion correction
  • TurboFLASH
  • n/a OA procedure


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