Reducing susceptibility artifacts in fMRI using volume-selective z-shim compensation

Magn Reson Med. 2007 Feb;57(2):396-404. doi: 10.1002/mrm.21150.

Abstract

Susceptibility-induced magnetic field gradients (SFGs) can result in severe signal loss in the orbitofrontal cortex (OFC) in gradient-echo-based functional MRI (fMRI) studies. Although conventional z-shim techniques can effectively recover the MRI signal in this region, the substantial penalty in imaging time hampers their use in routine fMRI studies. A modified z-shim technique with high imaging efficiency is presented in this study. In this technique, z-shim compensations are applied only to a selective volume where the susceptibility artifact is severe. The results of an fMRI study (N=6) demonstrate the feasibility of detecting the OFC activation with z-shim in whole-brain fMRI studies at a temporal resolution of 2 s.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Artifacts
  • Feasibility Studies
  • Female
  • Frontal Lobe / anatomy & histology*
  • Humans
  • Image Processing, Computer-Assisted*
  • Magnetic Resonance Imaging / methods*
  • Male
  • Middle Aged