科研之友
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摘要
We propose a whole-body transmit coil structure for two-channel B1 shimming at 3T. The transmit coil consists of four identical vertical-loop-coils placed on a cylindrical former by equiangular basis. A vertical loop coil consists of an inner-conductor plane and an outer-conductor plane both of which constitute a vertical loop when the two planes are connected by tuning capacitors at both ends. To improve the B1 homogeneity of the transmit coil, we split the inner- and outer-conductor planes into two rungs. We made the transmit coil with the length of 500 mm on a frame that had the inner and outer diameters of 550mm and 600mm, respectively. In the B1 shimming experiment with the transmit coil, we drove the coil with two RF power amplifiers of 18kWp each through two quadrature hybrids. Before the B1 shimming, we performed B1 mapping for each driving channel, and then, we determined the optimal magnitude and phase of the input signals to the RF power amplifiers. In the B1 shimming experiment on a human-body-mimicking phantom, the optimized transmission improved the image uniformity by 24.7% as compared to the conventional quadrature transmission.
- 出版日期2013-4
