Radiofrequency heating in porcine models with a "large" 32 cm internal diameter, 7 T (296 MHz) head coil

Devashish Shrivastava, Timothy Hanson, Jeramy Kulesa, Jinfeng Tian, Gregor Adriany, J. Thomas Vaughan

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Temperatures were measured in vivo in four pigs (mean animal weight = 110.75 kg and standard deviation = 6.13 kg) due to a continuous wave radiofrequency (RF) power irradiation with a 31.75 cm internal diameter and a 15.24 cm long, 7 T (296 MHz), eight channel, transverse electromagnetic head coil. The temperatures were measured in the subcutaneous layer of the scalp, 5, 10, 15, and 20 mm deep in the brain, and rectum using fluoroptic temperature probes. The RF power was delivered to the pig's head for ∼3 h (mean deposition time = 3.14 h and standard deviation = 0.06 h) at the whole head average specific absorption rate of ∼3 W kg-1 (mean average specific absorption rate = 3.08 W kg-1 and standard deviation = 0.09 W kg-1). Next, simple bioheat transfer models were used to simulate the RF power induced temperature changes. Results show that the RF power produced uniform temperature changes in the pigs' heads (mean temperature change = 1.68°C and standard deviation = 0.13°C) with no plateau achieved during the heating. No thermoregulatory alterations were detected due to the heating because the temperature responses of the pre-RF and post-RF epochs were not statistically significantly different. Simple, validated bioheat models may provide accurate temperature changes. Magn Reson Med, 2011. © 2011 Wiley-Liss, Inc.

Original languageEnglish (US)
Pages (from-to)255-263
Number of pages9
JournalMagnetic resonance in medicine
Volume66
Issue number1
DOIs
StatePublished - Jul 2011

Keywords

  • 7 T
  • MRI
  • bioheat
  • radiofrequency
  • safety

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