title: Correction of proton resonance frequency shift temperature maps for magnetic field disturbances using fat signal.
abstract: OBJECTIVE
  To improve the immunity of the proton resonance frequency shift (PRFS) method of MRI temperature mapping against magnetic field disturbances. Since PRFS is a phase-sensitive method, it misinterprets magnetic field disturbances as artifact temperature changes. If not corrected, the resulting temperature artifacts can completely obscure the true temperature estimation, especially if the temperature elevations are small.
  
  
  METHODS
  Since the fat protons experience the same magnetic field disturbances as the water protons, but no temperature-related frequency shift, the fat signal has been used for correcting PRFS temperature maps for the disturbances. A simple correction method is proposed that has either better compensation capability than the phase correction methods previously reported or higher spatial and temporal resolution than the spectroscopic correction methods previously reported. The evaluated method is based on the utilization of several gradient and spin echoes acquired within one repetition interval with water- and fat-selective scans.
  
  
  RESULTS
  In a series of phantom experiments, the improved method is shown to enable the reconstruction of accurate temperature maps in spite of interscan motion, suboptimal fat-water separation, and a wide range of magnetic field disturbances.
  
  
  CONCLUSIONS
  Our approach can be used for the guidance of thermal therapies involving tissues containing fat or surrounded by fat.
authors.affiliation: Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands. Andriy.Shmatukha@ge.com
authors.forename: Andriy V
authors.initials: AV
authors.lastname: Shmatukha
authors.forename: Paul R
authors.initials: PR
authors.lastname: Harvey
authors.forename: Chris J G
authors.initials: CJ
authors.lastname: Bakker
mesh_terms: D000818:Animals; D016477:Artifacts; D002138:Calibration; D004574:Electromagnetic Fields; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007834:Lasers; D008055:Lipids; D008099:Liver; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008280:Magnetics; D008383:Margarine; D008953:Models, Anatomic; D019047:Phantoms, Imaging; D011522:Protons; D012680:Sensitivity and Specificity; D013552:Swine; D013696:Temperature; D014867:Water
chemical_list: D008055:Lipids; D011522:Protons; D014867:Water; D008383:Margarine