Noninvasive temperature mapping with MRI using chemical shift water-fat separation

Brian J. Soher, Cory Wyatt, Scott B. Reeder, James R. MacFall

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

Tissues containing both water and lipids, e.g., breast, confound standard MR proton reference frequency-shift methods for mapping temperatures due to the lack of temperatureinduced frequency shift in lipid protons. Generalized Dixon chemical shift-based water-fat separation methods, such as GE's iterative decomposition of water and fat with echo asymmetry and least-squares estimation method, can result in complex water and fat images. Once separated, the phase change over time of the water signal can be used to map temperature. Phase change of the lipid signal can be used to correct for non-temperature-dependent phase changes, such as amplitude of static field drift. In this work, an image acquisition and postprocessing method, called water and fat thermal MRI, is demonstrated in phantoms containing 30:70, 50:50, and 70:30 water-to-fat by volume. Noninvasive heating was applied in an Off1-On-Off2 pattern over 50 min, using a miniannular phased radiofrequency array. Temperature changes were referenced to the first image acquisition. Four fiber optic temperature probes were placed inside the phantoms for temperature comparison. Region of interest (ROI) temperature values colocated with the probes showed excellent agreement (global mean ± standard deviation: -0.09 ± 0.34°C) despite significant amplitude of static field drift during the experiments.

Original languageEnglish (US)
Pages (from-to)1238-1246
Number of pages9
JournalMagnetic Resonance in Medicine
Volume63
Issue number5
DOIs
StatePublished - May 2010
Externally publishedYes

Keywords

  • Chemical shift
  • Hyperthermia
  • MR thermometry
  • PRFS
  • Water-fat separated imaging

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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