在3T（123.2兆赫兹）鸟笼式全身线圈中对猪进行体内射频加热。
In vivo radiofrequency heating in swine in a 3T (123.2-MHz) birdcage whole body coil.
作者信息
Shrivastava Devashish, Utecht Lynn, Tian Jinfeng, Hughes John, Vaughan J Thomas
机构信息
Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, Minnesota, USA.
出版信息
Magn Reson Med. 2014 Oct;72(4):1141-50. doi: 10.1002/mrm.24999. Epub 2013 Nov 20.
PURPOSE
To study in vivo radiofrequency (RF) heating produced due to power deposition from a 3T (Larmour frequency = 123.2 MHz), birdcage, whole body coil.
METHODS
The RF heating was simulated in a digital swine by solving the mechanistic generic bioheat transfer model (GBHTM) and the conventional, empirical Pennes bioheat transfer equation for two cases: 1) when the swine head was in the isocenter and 2) when the swine trunk was in the isocenter. The simulation results were validated by making direct fluoroptic temperature measurements in the skin, brain, simulated hot regions, and rectum of 10 swine (case 1: n = 5, mean animal weight = 84.03 ± 6.85 kg, whole body average SAR = 2.65 ± 0.22 W/kg; case 2: n = 5, mean animal weight = 81.59 ± 6.23 kg, whole body average SAR = 2.77 ± 0.26 W/kg) during 1 h of exposure to a turbo spin echo sequence.
RESULTS
The GBHTM simulated the RF heating more accurately compared with the Pennes equation. In vivo temperatures exceeded safe temperature thresholds with allowable SAR exposures. Hot regions may be produced deep inside the body, away from the skin.
CONCLUSION
SAR exposures that produce safe temperature thresholds need reinvestigation.
目的
研究3T（拉莫尔频率 = 123.2 MHz）鸟笼式全身线圈的功率沉积所产生的体内射频（RF）加热。
方法
通过求解机理通用生物热传递模型（GBHTM）和传统的经验性彭尼斯生物热传递方程，在数字猪模型中模拟RF加热，分为两种情况：1）猪头位于等中心时；2）猪躯干位于等中心时。通过对10头猪（情况1：n = 5，平均动物体重 = 84.03 ± 6.85 kg，全身平均比吸收率 = 2.65 ± 0.22 W/kg；情况2：n = 5，平均动物体重 = 81.59 ± 6.23 kg，全身平均比吸收率 = 2.77 ± 0.26 W/kg）在暴露于涡轮自旋回波序列1小时期间进行皮肤、大脑、模拟热区和直肠的直接荧光温度测量，对模拟结果进行验证。
结果
与彭尼斯方程相比，GBHTM对RF加热的模拟更准确。在允许的比吸收率暴露下，体内温度超过了安全温度阈值。热区可能在远离皮肤的身体深处产生。
结论
产生安全温度阈值的比吸收率暴露需要重新研究。
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