Ultra fast electromagnetic field computations for RF multi-transmit techniques in high field MRI
Ultra fast electromagnetic field computations for RF multi-transmit techniques in high field MRI
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DOI：
10.1088/0031-9155/54/5/010
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发表时间：
2009-03-07
影响因子：
3.5
通讯作者：
Van den Berg, Cornelis A. T.
中科院分区：
文献类型：
--
作者：
van den Bergen, Bob;Stolk, Christiaan C.;Van den Berg, Cornelis A. T.
提出了一种新的、非常快速的核磁共振成像电磁激励场计算方法。将计算域划分为不同的齐次区域，每个区域的通解由合适的基函数求和得到。通过在不同区域之间施加适当的边界条件，得到了电磁场的唯一解。方法结合的速度分析方法与全波仿真方法的通用性和验证在骨盆在3和7 T对数值模拟和测量3 T高速和准确测量的再生产和FDTD计算被认为提供大的可能性multi-transmit应用程序,它可以用于在线控制的全局和局部电场和特定吸收率(SAR)的病人。以该方法为例，利用7t仿真结果对射频振荡进行了评估，结果表明，磁场激励可以均匀化，而局部和平均SAR都降低了38%以上。
A new, very fast, approach for calculations of the electromagnetic excitation field for MRI is presented. The calculation domain is divided in different homogeneous regions, where for each region a general solution is obtained by a summation of suitable basis functions. A unique solution for the electromagnetic field is found by enforcing the appropriate boundary conditions between the different regions. The method combines the speed of an analytical method with the versatility of full wave simulation methods and is validated in the pelvic region against FDTD simulations at 3 and 7 T and measurements at 3 T. The high speed and accurate reproduction of measurements and FDTD calculations are believed to offer large possibilities for multi-transmit applications, where it can be used for on-line control of the global and local electric field and specific absorption rate (SAR) in the patient. As an example the method was evaluated for RF shimming with the use of 7 T simulation results, where it was demonstrated that the magnetic excitation field could be homogenized, while both the local and average SAR were reduced by 38% or more.