Three‐layered radio frequency coil arrangement for sodium MRI of the human brain at 9.4 Tesla

Abstract

PurposeA multinuclei imaging setup with the capability to acquire both sodium (23Na) and proton (1H) signals at 9.4 Tesla is presented. The main objective was to optimize coil performance at the 23Na frequency while still having the ability to acquire satisfactory 1H images.MethodsThe setup consisted of a combination of three radio frequency (RF) coils arranged in three layers: the innermost layer was a 27‐channel 23Na receive helmet which was surrounded by a four‐channel 23Na transceiver array. The outer layer consisted of a four‐channel 1H dipole array for B0 shimming and anatomical localization. Transmit and receive performance of the 23Na arrays was compared to a single‐tuned 23Na birdcage resonator.ResultsWhile the transmit efficiency of the 23Na transceiver array was comparable to the birdcage, the 23Na receive array provided substantial signal‐to‐noise ratio (SNR) gain near the surface and comparable SNR in the center. The utility of this customized setup was demonstrated by 23Na images of excellent quality.ConclusionHigh SNR, efficient transmit excitation and B0 shimming capability can be achieved for 23Na MRI at 9.4T using novel coil combination. This RF configuration is easily adaptable to other multinuclei applications at ultra high field (≥ 7T). Magn Reson Med 75:906–916, 2016. © 2015 Wiley Periodicals, Inc.