Port Decoupling vs Array Elements Decoupling for Tx/Rx System at 7-Tesla Magnetic Resonance Imaging

Abstract

Symmetrically excited meandered microstrip line RF coil elements are widely used in multichannel approaches; i.e., being integrated in ultra-high field magnetic resonance imaging (MRI) systems (i.e., 7-Tesla and higher). These elements have demonstrated strong magnetic field in deep areas through the object under imaging. Designing a radio frequency (RF) coil array that employs these elements without decoupling networks might cause non-optimized driving performance of coil array which in turn result in non-clear image. In this paper, two different methods of decoupling are studied: port decoupling and array elements decoupling. In the first one, the coil elements are designed at Larmor frequency (297.3 MHz), while in the other one, the coil elements are designed at higher frequencies but matched at Larmor frequency. Port decoupling does not always mean element decoupling. Conventional decoupling methods, such as single capacitor or inductor, face challenges to realize the coil element decoupling for meandered microstrip arrays. An optimized reactive (T-shaped) network is needed in order to achieve element decoupling which in turn prevents distortion of the EM field. All simulation results have been obtained using the CST time domain solver (CST AG, Darmstadt, Germany).