Hybrid Monopole/Loop Coil Array for Human Head MR Imaging at 7 T

Abstract

The monopole coil and loop coil have orthogonal radiofrequency (RF) fields and thus are intrinsically decoupled electromagnetically if they are laid out appropriately. In this study, we proposed a hybrid monopole/loop technique which could combine the advantages of both loop arrays and monopole arrays. To investigate this technique, a hybrid RF coil array containing 4 monopole channels and 4 loop channels was developed for human head MR imaging at 7T. In vivo MR imaging and g-factor results using monopole-only channels, loop-only channels and all channels of the hybrid array were acquired and evaluated. Compared with the monopole-only and loop-only channels, the proposed hybrid array has higher SNR and better parallel imaging performance. Sufficient electromagnetic decoupling and diverse RF magnetic field (B1) distributions of monopole channels and loop channels may contribute to this performance improvement. From experimental results, the hybrid monopole/loop array has low g-factor and excellent SNR at both periphery and center of the brain, which is valuable for human head imaging at ultrahigh fields.

Sensitivity enhancement of traveling wave MRI using free local resonators: an experimental demonstration

“…Unlike the element layout shown in Figure 6 where the two elements were placed orthogonally and thus intrinsically decoupled, when more resonant elements are involved, electromagnetic coupling among elements may become an issue. This coupling issue can be possibly addressed by using the magnetic wall or ICE decoupling technology reported in literatures (24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35). i.e.…”

Closely Spaced Double-Row Microstrip RF Arrays for Parallel MR Imaging at Ultrahigh Fields

“…Microstrip line resonators were chosen as the basic coil elements and ICE/magnetic wall method was used for decoupling. ICE/magnetic wall decoupling has proven to be a general decoupling method, and has been successfully applied for almost all kinds of RF coils in MRI, including L/C loop, microstrip line, monopole and dipole coils [23, 24, 33, 34]. In previous ICE-decoupled RF array designs, decoupling elements were placed between two coupled coil elements.…”

Simulation Verification of SNR and Parallel Imaging Improvements by ICE-Decoupled Loop Array in MRI

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