Compensating for magnetic field inhomogeneity in multigradient-echo-based MR thermometry

Frank F J Simonis, Esben T Petersen, LW Bartels, JJW Lagendijk, CAT van den Berg

Research output: Contribution to journalArticleAcademicpeer-review


PURPOSE: MR thermometry (MRT) is a noninvasive method for measuring temperature that can potentially be used for radio frequency (RF) safety monitoring. This application requires measuring absolute temperature. In this study, a multigradient-echo (mGE) MRT sequence was used for that purpose. A drawback of this sequence, however, is that its accuracy is affected by background gradients. In this article, we present a method to minimize this effect and to improve absolute temperature measurements using MRI.

THEORY: By determining background gradients using a B0 map or by combining data acquired with two opposing readout directions, the error can be removed in a homogenous phantom, thus improving temperature maps.

METHODS: All scans were performed on a 3T system using ethylene glycol-filled phantoms. Background gradients were varied, and one phantom was uniformly heated to validate both compensation approaches. Independent temperature recordings were made with optical probes.

RESULTS: Errors correlated closely to the background gradients in all experiments. Temperature distributions showed a much smaller standard deviation when the corrections were applied (0.21°C vs. 0.45°C) and correlated well with thermo-optical probes.

CONCLUSION: The corrections offer the possibility to measure RF heating in phantoms more precisely. This allows mGE MRT to become a valuable tool in RF safety assessment.

Original languageEnglish
Pages (from-to)1184-9
Number of pages6
JournalMagnetic Resonance in Medicine
Issue number3
Publication statusPublished - 2015


  • Algorithms
  • Artifacts
  • Echo-Planar Imaging
  • Humans
  • Image Enhancement
  • Image Interpretation, Computer-Assisted
  • Magnetic Fields
  • Nonlinear Dynamics
  • Phantoms, Imaging
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Signal Processing, Computer-Assisted
  • Thermography


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