Van den Berg Cornelis A T, Bartels Lambertus W, van den Bergen Bob, Kroeze Hugo, de Leeuw Astrid A C, Van de Kamer Jeroen B, Lagendijk Jan J W
Department of Radiotherapy, University Medical Center Utrecht, PO Box 85500, HP Q.00.118 3508 GA Utrecht, The Netherlands.
Phys Med Biol. 2006 Oct 7;51(19):4735-46. doi: 10.1088/0031-9155/51/19/001. Epub 2006 Sep 5.
In this study, MR B(+)(1) imaging is employed to experimentally verify the validity of FDTD simulations of electromagnetic field patterns in human anatomies. Measurements and FDTD simulations of the B(+)(1) field induced by a 3 T MR body coil in a human corpse were performed. It was found that MR B(+)(1) imaging is a sensitive method to measure the radiofrequency (RF) magnetic field inside a human anatomy with a precision of approximately 3.5%. A good correlation was found between the B(+)(1) measurements and FDTD simulations. The measured B(+)(1) pattern for a human pelvis consisted of a global, diagonal modulation pattern plus local B(+)(1) heterogeneties. It is believed that these local B(+)(1) field variations are the result of peaks in the induced electric currents, which could not be resolved by the FDTD simulations on a 5 mm(3) simulation grid. The findings from this study demonstrate that B(+)(1) imaging is a valuable experimental technique to gain more knowledge about the dielectric interaction of RF fields with the human anatomy.
在本研究中，采用磁共振B(+)(1)成像来实验验证人体解剖结构中电磁场模式的时域有限差分（FDTD）模拟的有效性。对一具人体尸体中由3T磁共振体线圈感应产生的B(+)(1)场进行了测量和FDTD模拟。结果发现，磁共振B(+)(1)成像是一种测量人体解剖结构内射频（RF）磁场的灵敏方法，精度约为3.5%。在B(+)(1)测量值与FDTD模拟之间发现了良好的相关性。人体骨盆的测量B(+)(1)模式由整体对角调制模式加上局部B(+)(1)不均匀性组成。据信，这些局部B(+)(1)场变化是感应电流峰值的结果，在5mm(3)模拟网格上的FDTD模拟无法解析这些峰值。本研究结果表明，B(+)(1)成像是一种有价值的实验技术，可用于获取更多关于射频场与人体解剖结构介电相互作用的知识。
