Abstract

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Title:: Design of a radiofrequency coil for low-field magnetic resonance imaging by target-field method combined with CST simulation

Author(s):: ZHANG Xun1; HU Liangliang2; QU Zheng3; XU Jinzhang1; 1. School of Electrical Engineering and Automation, Hefei University of Technology, Hefei 230000, China 2. School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology, Hefei 230000, China 3. School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China

Keywords:: Keywords: low-field magnetic resonance imaging radiofrequency coil target-field method CST software field-circuit co-simulation quality factor

Abstract:: Abstract: According to the clinical needs of human lung MRI, a 3He radiofrequency (RF) coil was designed for 0.06 T low-field magnetic resonance imaging of the lung. By predefining the region of interest and its internal target magnetic field, the inverse solution of source current density distribution of the target magnetic field generated in the region of interest is obtained using target-field method and the ideal winding of the RF coil is determined by stream function. Then, CST software is employed to model and simplify the coil winding, and field-circuit co-simulation is applied to study the performance indicators of load RF coil, such as RF field (B1) and specific absorption rate distribution under different quality factors (Q factors). The simulation results show that the Q factor of the coil can be adjusted by changing the capacitance value of the RF circuit. As Q factor of the coil get larger, there are higher B1 field intensity generated under the excitation of the unit power signal, higher specific absorption rate and lower transmission efficiency, while B1 field uniformity is not affected by Q factor and always keeps at nearly 90%. The feasibility of the design by target-field method combined with CST simulation is verified by RF coil simulation, and the proposed method can be promoted to high-frequency RF coil design.