title: Measurement of proton resonance frequency shift coefficient during MR-guided focused ultrasound on Thiel embalmed tissue.
abstract: OBJECTIVE
  To estimate the value of proton resonance frequency (PRF) shift coefficient of explanted Thiel embalmed animal and human tissue used as a preclinical model for treatment with MR-guided focused ultrasound (FUS).
  
  
  METHODS
  Thiel embalmed human liver, ovine liver, and porcine muscle were heated using two methods: bulk heating and FUS-induced heating. Phase-referenced PRF thermometry was applied during cooling of the tissue to obtain a series of phase difference, ΔΦ, maps. A fiber-optic thermocouple was inserted in the tissue to measure the temperature difference, ΔT. The PRF shift coefficient was calculated from the measured ΔΦ, ΔT.
  
  
  RESULTS
  In the case of bulk heating, the mean values (±SD) of the PRF coefficient for Thiel embalmed ovine liver, porcine muscle, and human liver were: 0.017 (5 × 10-4) ppm/°C, 0.015 (6 × 10-4) ppm/°C, and 0.012 (6 × 10-4) ppm/°C, respectively. Similar values were found in tissues heated with FUS.
  
  
  CONCLUSIONS
  The values of PRF coefficient measured for the Thiel embalmed tissue were higher than the values for fresh tissue, suggesting that embalming a tissue with Thiel fluid can affect PRF thermometry. The chemical composition of the Thiel fluid and the electrical conductivity may explain these results. Magn Reson Med 74:260-265, 2015. © 2014 Wiley Periodicals, Inc.
authors: Institute for Medical Science and Technology, University of Dundee, Dundee, United Kingdom.
authors: Ioannis
authors: I
authors: Karakitsios
authors: Institute for Medical Science and Technology, University of Dundee, Dundee, United Kingdom.
authors: Osnat
authors: O
authors: Dogadkin
authors: Institute for Medical Science and Technology, University of Dundee, Dundee, United Kingdom.
authors: Nhan
authors: N
authors: Le
authors: Institute for Medical Science and Technology, University of Dundee, Dundee, United Kingdom.
authors: Andreas
authors: A
authors: Melzer
keywords: MR-guided focused ultrasound; PRF shift coefficient; PRF thermometry; Thiel embalmed tissue