The effect of concomitant fields in fast spin echo acquisition on asymmetric MRI gradient systems

Shengzhen Tao, Paul T. Weavers, Joshua D. Trzasko, John Huston, Yunhong Shu, Erin M. Gray, Thomas K.F. Foo, Matt A. Bernstein

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Purpose: To investigate the effect of the asymmetric gradient concomitant fields (CF) with zeroth and first-order spatial dependence on fast/turbo spin-echo acquisitions, and to demonstrate the effectiveness of their real-time compensation. Methods: After briefly reviewing the CF produced by asymmetric gradients, the effects of the additional zeroth and first-order CFs on these systems are investigated using extended-phase graph simulations. Phantom and in vivo experiments are performed to corroborate the simulation. Experiments are performed before and after the real-time compensations using frequency tracking and gradient pre-emphasis to demonstrate their effectiveness in correcting the additional CFs. The interaction between the CFs and prescan-based correction to compensate for eddy currents is also investigated. Results: It is demonstrated that, unlike the second-order CFs on conventional gradients, the additional zeroth/first-order CFs on asymmetric gradients cause substantial signal loss and dark banding in fast spin-echo acquisitions within a typical brain-scan field of view. They can confound the prescan correction for eddy currents and degrade image quality. Performing real-time compensation successfully eliminates the artifacts. Conclusions: We demonstrate that the zeroth/first-order CFs specific to asymmetric gradients can cause substantial artifacts, including signal loss and dark bands for brain imaging. These effects can be corrected using real-time compensation. Magn Reson Med 79:1354–1364, 2018.

Original languageEnglish (US)
Pages (from-to)1354-1364
Number of pages11
JournalMagnetic Resonance in Medicine
Volume79
Issue number3
DOIs
StatePublished - Mar 2018

Keywords

  • EPG
  • FSE
  • TSE
  • asymmetric gradient
  • concomitant field
  • extended phase graph
  • fast spin echo
  • turbo spin echo

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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