期刊
MAGNETIC RESONANCE IN MEDICINE
卷 62, 期 4, 页码 888-895出版社
WILEY
DOI: 10.1002/mrm.22072
关键词
RF safety; RF heating; MR safety; ultra-high-field MRI; MR heating; 9.4T
资金
- National Institutes of Health (NIH)
- Keck Foundation
- [R01 CA94318]
- [R01 EB0000895]
- [R01 CA94200]
- [C06 RR12147]
- [C06 RR17557]
- [BTRR-P41 RR08079]
- [R01 EB006835]
- [R01 EB007327]
- [P41 RR08079]
In vivo thermoregulatory temperature response to radio frequency (RF) heating at 9.4T was studied by measuring temperatures in nine anesthetized swine. Temperatures were measured in the scalp, brain, and rectum. The RF energy was deposited using a four-loop head coil tuned to 400.2 MHz. Sham RF was delivered to three swine to understand the thermal effects of anesthesia (animal weight = 54.16 kg, SD = 3.08 kg). Continuous wave (CW) RF energy was delivered to the other animals for 2.5-3.4 h (animal weight = 74.01 +/- 26.0 kg, heating duration = 3.05 +/- 0.29 h). The whole-head specific absorption rate (SAR) varied between 2.71 W/kg and 3.20 W/kg (SAR = 2.93 +/- 0.18 W/kg). Anesthesia caused the brain and rectal temperatures to drop linearly. Altered thermoregulatory response was detected by comparing the difference in the temperature slopes before and after the RF delivery from zero. heating statistically significantly altered the rate of cooling down of the animal. The temperature slope changes well with the RF energy per unit head weight and heating duration, and the maximum rectal temperature change during heating in heated animals. The temperature slope changes did not correlate well to the whole-head average SARs. Magn Reson Med 62:888-895, 2009. (C) 2009 Wiley-Liss, Inc.
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