通过相控阵和体线圈同时传输提高发射场的均匀性。
Improved homogeneity of the transmit field by simultaneous transmission with phased array and volume coil.
机构信息
Department of Neurosurgery, Yale University, New Haven, CT 06519, USA.
出版信息
J Magn Reson Imaging. 2010 Aug;32(2):476-81. doi: 10.1002/jmri.22257.
PURPOSE
To improve the homogeneity of transmit volume coils at high magnetic fields (> or =4 T). Due to radiofrequency (RF) field/tissue interactions at high fields, 4 T to 8 T, the transmit profile from head-sized volume coils shows a distinctive pattern with relatively strong RF magnetic field B(1) in the center of the brain.
MATERIALS AND METHODS
In contrast to conventional volume coils at high field strengths, surface coil phased arrays can provide increased RF field strength peripherally. In theory, simultaneous transmission from these two devices could produce a more homogeneous transmission field. To minimize interactions between the phased array and the volume coil, counter rotating current (CRC) surface coils consisting of two parallel rings carrying opposite currents were used for the phased array.
RESULTS
Numerical simulations and experimental data demonstrate that substantial improvements in transmit field homogeneity can be obtained.
CONCLUSION
We have demonstrated the feasibility of using simultaneous transmission with human head-sized volume coils and CRC phased arrays to improve homogeneity of the transmit RF B(1) field for high-field MRI systems.
目的
提高高磁场（> = 4T）下发射容积线圈的均匀性。由于在高场（4T 至 8T）下射频（RF）场/组织相互作用，头大小容积线圈的发射分布呈现出独特的模式，大脑中心的相对较强的 RF 磁场 B（1）。
材料和方法
与高场强常规容积线圈相比，表面线圈相控阵可在周边提供更高的 RF 场强度。理论上，这两个设备的同时发射可以产生更均匀的发射场。为了最小化相控阵和容积线圈之间的相互作用，采用了由两个载流相反的平行环组成的反向电流（CRC）表面线圈作为相控阵。
结果
数值模拟和实验数据表明，发射场均匀性可以得到显著改善。
结论
我们已经证明了使用带有 CRC 相控阵的人头大小容积线圈同时传输以提高高场 MRI 系统发射 RF B（1）场均匀性的可行性。
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