Protocol to determine the optimal intraoral passive shim for minimisation of susceptibility artifact in human inferior frontal cortex

James L. Wilson, Mark Jenkinson, Peter Jezzard

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


At higher static magnetic field (B0) strengths (≥3 T), the study of human inferior frontal cortex (IFC) when utilising a variety of MRI techniques is severely hampered by the presence of susceptibility artifacts. This is particularly the case for blood oxygenation level-dependent functional MRI, where large signal voids are generally encountered in the frontal lobes. A previous study described an approach to artifact correction involving a mouth insert consisting of a prototype diamagnetic passive shim [Magn. Reson. Med. 48 (2002), 906]. Here we extend that method by investigating the effect of five different intraoral passive shims on B0 homogeneity and echoplanar imaging susceptibility artifacts within the brain, and particularly the IFC, of six subjects. The optimal passive shim is shown to be subject- and study-specific, providing an average reduction in mean absolute B0 offset within the IFC of 57%, along with a concomitant reduction in echoplanar susceptibility artifact. All subjects were at ease while wearing the intraoral shims. A 4-min in vivo protocol to determine the optimal passive shim from the available set, utilising intrinsic structural and B0 subject data, is described and shown to be accurate and reliable.

Original languageEnglish
Pages (from-to)1802-1811
Number of pages10
Issue number4
Publication statusPublished or Issued - 1 Aug 2003
Externally publishedYes


  • Diamagnetic
  • Frontal lobes
  • Shimming
  • Susceptibility artifact
  • fMRI

ASJC Scopus subject areas

  • Neurology
  • Cognitive Neuroscience

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