A specific absorption rate prediction concept for parallel transmission MR
A specific absorption rate prediction concept for parallel transmission MR
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DOI：
10.1002/mrm.24138
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发表时间：
2012-11-01
影响因子：
3.3
通讯作者：
Katscher, Ulrich
中科院分区：
文献类型：
--
作者：
Graesslin, Ingmar;Homann, Hanno;Katscher, Ulrich
特定吸收率（SAR）是高场MR中的限制因素。SAR估计通常通过使用通用人体模型的数值模拟来执行。然而，单通道射频传输的SAR概念不能直接应用于多通道系统。在这项研究中，提出了一种新的和全面的并行射频传输MRI的SAR预测概念，根据预先计算的磁场和电场从数值人体模型的电磁仿真。所谓的Q矩阵的应用和进一步的计算优化允许在扫描之前对SAR进行实时估计。该SAR估计方法被完全集成到八通道全身MRI系统中，并且它便于选择不同的身体模型和身体位置。在幻影的全球SAR的实验验证表现出良好的定性和定量的预测协议。初始体内确认显示（激励）射频场的模拟和测量振幅之间具有良好的定性一致性。该SAR预测概念的可行性和实用性已在2012年的高场MR Magn Reson Med中显示，为安全并行射频传输铺平了道路。(c)2012 Wiley Periodicals，Inc.
The specific absorption rate (SAR) is a limiting factor in high-field MR. SAR estimation is typically performed by numerical simulations using generic human body models. However, SAR concepts for single-channel radiofrequency transmission cannot be directly applied to multichannel systems. In this study, a novel and comprehensive SAR prediction concept for parallel radiofrequency transmission MRI is presented, based on precalculated magnetic and electric fields obtained from electromagnetic simulations of numerical body models. The application of so-called Q-matrices and further computational optimizations allow for a real-time estimation of the SAR prior to scanning. This SAR estimation method was fully integrated into an eight-channel whole body MRI system, and it facilitated the selection of different body models and body positions. Experimental validation of the global SAR in phantoms demonstrated a good qualitative and quantitative agreement with the predictions. An initial in vivo validation showed good qualitative agreement between simulated and measured amplitude of (excitation) radiofrequency field. The feasibility and practicability of this SAR prediction concept was shown paving the way for safe parallel radiofrequency transmission in high-field MR. Magn Reson Med, 2012. (c) 2012 Wiley Periodicals, Inc.