Development of a proton‐frequency‐transparent birdcage radiofrequency coil for in vivo13c mrs/mrsi study in a 3.0 t mri system

Abstract

A proton‐frequency‐transparent (PFT) birdcage RF coil that contains carbon‐proton switching circuits (CPSCs) is presented to acquire13C MR signals, which, in turn, enable1H imaging with existing1H RF coils without being affected by a transparent13C birdcage RF coil. CPSCs were installed in the PFT13 C birdcage RF coil to cut the RF coil circuits during1 H MR imaging. Finite-difference time‐domain (FDTD) electromagnetic (EM) simulations were performed to verify the performance of the proposed CPSCs. The performance of the PFT13 C birdcage RF coil with CPSCs was verified via phantom and in vivo MR studies. In the phantom MR studies,1H MR images and 13 C MR spectra were acquired and compared with each other using the13C birdcage RF coil with and without the CPSCs. For the in vivo MR studies, hyperpolarized13C cardiac MRS and MRSI of swine were performed. The proposed PFT13C birdcage RF coil with CPSCs led to a percent image uniformity (PIU) reduction of 1.53% in the proton MR images when compared with the case without it. FDTD EM simulations revealed PIU reduction of 0.06% under the same conditions as the phantom MR studies. Furthermore, an SNR reduction of 5.5% was observed at13C MR spectra of corn‐oil phantom using the PFT13C birdcage RF coil with CPSCs compared with that of the13 C birdcage RF coil without CPSCs. Utilizing the PFT13C birdcage RF coil,13 C‐enriched compounds were successfully acquired via in vivo hyperpolarized13 C MRS/MRSI experiments. In conclusion, the applicability and utility of the proposed 16‐leg low‐pass PFT13C birdcage RF coil with CPSCs were verified via1H MR imaging and hyperpolarized13 C MRS/MRSI studies using a 3.0 T MRI system.