title: Accurate MR thermometry by hyperpolarized129Xe.
abstract: To investigate the temperature dependence of the resonance frequency of lipid-dissolved xenon (LDX) and to assess the accuracy of LDX-based MR thermometry.
  
  
  
  The chemical shift temperature dependence of water protons, methylene protons, and LDX was measured from samples containing tissues with varying fat contents using a high-resolution NMR spectrometer. LDX results were then used to acquire relative and absolute temperature maps in vivo and the results were compared with PRF-based MR thermometry.
  
  
  
  The temperature dependence of proton resonance frequency (PRF) is strongly affected by the specific distribution of water and fat. A redistribution of water and fat compartments can reduce the apparent temperature dependence of the water chemical shift from -0.01 ppm/°C to -0.006 ppm, whereas the LDX chemical shift shows a consistent temperature dependence of -0.21 ppm/°C. The use of the methylene protons resonance frequency as internal reference improves the accuracy of LDX-based MR thermometry, but degrades that of PRF-based MR thermometry, as microscopic susceptibility gradients affected lipid and water spins differently.
  
  
  
  The LDX resonance frequency, with its higher temperature dependence, provides more accurate and precise temperature measurements, both in vitro and in vivo. More importantly, the resonance frequency of nearby methylene protons can be used to extract absolute temperature information. Magn Reson Med 78:1070-1079, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Applied Physical Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.|Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Le
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.|Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Burant
authors.affiliation: Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.|Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: McCallister
authors.affiliation: Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Victor
authors.initials: V
authors.lastname: Zhao
authors.affiliation: Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Karl M
authors.initials: KM
authors.lastname: Koshlap
authors.affiliation: Center for Molecular and Biomolecular Imaging, Department of Radiology and Dermatology, Duke University, Durham, North Carolina, USA.
authors.forename: Simone
authors.initials: S
authors.lastname: Degan
authors.affiliation: Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.|Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Antonacci
authors.affiliation: Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.|Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Rosa Tamara
authors.initials: RT
authors.lastname: Branca
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging; D000818:Animals; D001831:Body Temperature / Q000502:physiology; D003198:Computer Simulation; D005260:Female; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008820:Mice, Obese; D011522:Protons; D062125:Thermometry / Q000379:methods*; D014979:Xenon Isotopes / Q000737:chemistry* / Q000378:metabolism
chemical_list: D011522:Protons; D014979:Xenon Isotopes
keywords: MR thermometry; adipose tissue; proton resonance frequency shift; xenon