Cho Chie-Hee, Grosse-Siestrup Christian, Nadobny Jacek, Lojewski Christian, Niehus Stefan Markus, Taupitz Matthias, Hamm Bernd, Schlattmann Peter
Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Institute for Diagnostic and Interventional Radiology, University Clinic Jena, Jena, Germany.
Bioelectromagnetics. 2021 Jan;42(1):37-50. doi: 10.1002/bem.22311. Epub 2020 Dec 20.
Exposure to radiofrequency (RF) power deposition during magnetic resonance imaging (MRI) induces elevated body-tissue temperatures and may cause changes in heart and breathing rates, disturbing thermoregulation. Eleven temperature sensors were placed in muscle tissue and one sensor in the rectum (measured in 10 cm depth) of 20 free-breathing anesthetized pigs to verify temperature curves during RF exposure. Tissue temperatures and heart and breathing rates were measured before, during, and after RF exposure. Pigs were placed into a 60-cm diameter whole-body resonator of a 3 T MRI system. Nineteen anesthetized pigs were divided into four RF exposure groups: sham (0 W/kg), low-exposure (2.7 W/kg, mean exposure time 56 min), moderate-exposure (4.8 W/kg, mean exposure time 31 min), and high-exposure (4.4 W/kg, mean exposure time 61 min). One pig was exposed to a whole-body specific absorption rate (wbSAR) of 11.4 W/kg (extreme-exposure). Hotspot temperatures, measured by sensor 2, increased by mean 5.0 ± 0.9°C, min 3.9; max 6.3 (low), 7.0 ± 2.3°C, min 4.6; max 9.9 (moderate), and 9.2 ± 4.4°C, min 6.1, max 17.9 (high) compared with 0.3 ± 0.3°C in the sham-exposure group (min 0.1, max 0.6). Four time-temperature curves were identified: sinusoidal, parabolic, plateau, and linear. These curve shapes did not correlate with RF intensity, rectal temperature, breathing rate, or heart rate. In all pigs, rectal temperatures increased (2.1 ± 0.9°C) during and even after RF exposure, while hotspot temperatures decreased after exposure. When rectal temperature increased by 1°C, hotspot temperature increased up to 42.8°C within 37 min (low-exposure) or up to 43.8°C within 24 min (high-exposure). Global wbSAR did not correlate with maximum hotspot. Bioelectromagnetics. 2021;42:37-50. © 2020 The Authors. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society.
在磁共振成像（MRI）过程中暴露于射频（RF）功率沉积会导致人体组织温度升高，并可能引起心率和呼吸频率变化，干扰体温调节。在20头自主呼吸的麻醉猪的肌肉组织中放置了11个温度传感器，并在直肠（深度为10厘米处测量）放置了1个传感器，以验证射频暴露期间的温度曲线。在射频暴露前、暴露期间和暴露后测量组织温度、心率和呼吸频率。将猪放入一台3T MRI系统的直径60厘米的全身共振器中。19头麻醉猪被分为四个射频暴露组：假暴露组（0瓦/千克）、低暴露组（2.7瓦/千克，平均暴露时间56分钟）、中暴露组（4.8瓦/千克，平均暴露时间31分钟）和高暴露组（4.4瓦/千克，平均暴露时间61分钟）。一头猪暴露于全身比吸收率（wbSAR）为11.4瓦/千克（极端暴露）。由传感器2测量的热点温度平均升高了5.0±0.9°C，最低3.9°C；最高6.3°C（低暴露组），7.0±2.3°C，最低4.6°C；最高9.9°C（中暴露组），以及9.2±4.4°C，最低6.1°C，最高17.9°C（高暴露组），而假暴露组为0.3±0.3°C（最低0.1°C，最高0.6°C）。确定了四种时间-温度曲线：正弦曲线、抛物线曲线、平台曲线和线性曲线。这些曲线形状与射频强度、直肠温度、呼吸频率或心率均无关联。在所有猪中，直肠温度在射频暴露期间甚至暴露后都有所升高（2.1±0.9°C），而热点温度在暴露后下降。当直肠温度升高1°C时，热点温度在37分钟内升高至42.8°C（低暴露组）或在24分钟内升高至43.8°C（高暴露组）。总体wbSAR与最大热点温度无关。《生物电磁学》。2021年；42:37 - 50。© 2020作者。《生物电磁学》由威利期刊有限责任公司代表生物电磁学协会出版。
