Shen G X, Boada F E, Thulborn K R
Department of Radiology, University of Pittsburgh Medical Center, PA 15213, USA.
Magn Reson Med. 1997 Nov;38(5):717-25. doi: 10.1002/mrm.1910380507.
Rapid quantification of tissue metabolites in vivo by MRS or MRI can be achieved using dual-frequency RF coils with identical B1 field distributions at the observation frequencies of the metabolites and tissue water protons. Tissue sodium is used as an example for optimizing the dual-frequency, dual-quadrature RF coils for such measurements in humans. In the setting of sodium imaging, the challenge of dual-quadrature birdcage configurations is to decouple the sodium and proton channels because the fourth harmonic of the sodium frequency is very close to the proton frequency. A generalizable method for effectively decoupling these two RF frequencies is presented in this paper. The method is demonstrated with the design of an EPI compatible, dual-quadrature, double-tuned, 23Na/1H birdcage coil. The performance of the RF probe is reported at 1.5 Tesla in terms of signal-to-noise ratio, B1 homogeneity and image quality.
通过磁共振波谱（MRS）或磁共振成像（MRI）在体内快速定量组织代谢物，可以使用在代谢物和组织水质子的观测频率下具有相同B1场分布的双频射频线圈来实现。以组织钠为例，优化用于人体此类测量的双频、双正交射频线圈。在钠成像的情况下，双正交鸟笼配置的挑战在于解耦钠和质子通道，因为钠频率的四阶谐波非常接近质子频率。本文提出了一种有效解耦这两个射频频率的通用方法。该方法通过设计一个与回波平面成像（EPI）兼容的、双正交、双调谐、23Na/1H鸟笼线圈进行了演示。在1.5特斯拉的条件下，报告了该射频探头在信噪比、B1均匀性和图像质量方面的性能。
