Prediction of specific absorption rate in mother and fetus associated with MRI examinations during pregnancy
Prediction of specific absorption rate in mother and fetus associated with MRI examinations during pregnancy
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DOI：
10.1002/mrm.20824
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发表时间：
2006-04-01
影响因子：
3.3
通讯作者：
Hajnal, JV
中科院分区：
文献类型：
--
作者：
Hand, JW;Li, Y;Hajnal, JV
关于核磁共振成像（MRI）检查对孕妇的风险存在不确定性。最常用的方法，如单次快速自旋回波（ssFSE），通常需要在安全指南规定的特定吸收率（SAR）限制下操作。随着高视场系统的引入，这些限制将对胎儿成像更加重要。基于时域有限积分技术（FIT）的电磁求解器用于预测孕妇（妊娠28周）解剖学真实模型的SAR，该模型与典型的1.5 T和3t MRI系统（即分别在大约64和127 MHz工作）的鸟笼体线圈的射频（RF）场相关。结果表明：1)母亲的局部SAR最高，胎儿在64 MHz时的峰值约为该值的40-60%，在127 MHz时增加到约50-70%；2)符合美国食品和药物管理局（FDA）和国际非电离辐射防护委员会（ICNIRP）的指导方针，要求控制平均SAR值分别超过1 g或10 g的组织；3)符合医疗器械管理局（MDA）的指导方针，要求控制胎儿体内的最大SAR（10g）。
There is uncertainty regarding the risk posed by magnetic resonance imaging (MRI) examinations to pregnant patients. The most frequently used methods, such as single-shot fast spin echo (ssFSE), often require operation at the specific absorption rate (SAR) limits imposed by safety guidelines. With the introduction of higher-field systems, such limits will be even more significant for fetal imaging. An electromagnetic solver based on the time domain finite integration technique (FIT) was used to predict SAR in an anatomically realistic model of a pregnant patient (28 weeks' gestation) associated with the radiofrequency (RF) fields from birdcage body coils typical of 1.5 T and 3 T MRI systems (i.e., operating at approximately 64 and 127 MHz, respectively). The results suggest that 1) the highest local SAR is in the mother, with the fetus being exposed to a peak of approximately 40-60% of that value at 64 MHz, increasing to approximately 50-70% at 127 MHz; 2) compliance with U.S. Food and Drug Administration (FDA) and International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines requires control of SAR values averaged over I g or 10 g of tissue, respectively; and 3) compliance with Medical Device Agency (MDA) guidelines requires control of the maximum SAR(10g) within the fetus.