Correction for eddy current induced Bo shifts in diffusion-weighted echo-planar imaging

Magn Reson Med. 1999 Jan;41(1):95-102. doi: 10.1002/(sici)1522-2594(199901)41:1<95::aid-mrm14>;2-t.


The importance of diffusion-weighted MRI in the assessment of acute stroke is well-recognized, and quantitative maps of the apparent diffusion coefficient (ADC) are now widely used. Echoplanar imaging provides a robust method of acquiring diffusion-weighted images free of motion artifact. However, initial experience with clinical MRI systems indicates that calculation of artifact-free ADC maps from a series of echo-planar diffusion-weighted images is not necessarily straight-forward. One of the problems is that frequency shifts resulting from eddy currents can cause misregistration of base diffusion-weighted images. In this study, an on-line correction method that overcomes this problem is described, and phantom and human images that demonstrate the validity of the technique are presented. The method uses a non-phase-encoded reference scan to correct the phase of each echo in the echo train, and can provide ADC maps that are free of misregistration artifacts, without the need for off-line postprocessing.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anisotropy
  • Artifacts
  • Basal Ganglia / pathology
  • Brain / pathology*
  • Cerebrovascular Disorders / diagnosis
  • Child
  • Echo-Planar Imaging*
  • Female
  • Follow-Up Studies
  • Humans
  • Image Processing, Computer-Assisted
  • Phantoms, Imaging
  • Reproducibility of Results