13C MRS of human brain at 7 Tesla using [2-13C]glucose infusion and low power broadband stochastic proton decoupling

Abstract

Purpose Carbon-13 (13C) MR spectroscopy (MRS) of the human brain at 7 Tesla (T) may pose patient safety issues due to high radiofrequency (RF) power deposition for proton decoupling. The purpose of present work is to study the feasibility of in vivo 13C MRS of human brain at 7 T using broadband low RF power proton decoupling. Methods Carboxylic/amide 13C MRS of human brain by broadband stochastic proton decoupling was demonstrated on a 7 T scanner. RF safety was evaluated using the finite-difference time-domain method. 13C signal enhancement by nuclear Overhauser effect (NOE) and proton decoupling was evaluated in both phantoms and in vivo. Results At 7 T, the peak amplitude of carboxylic/amide 13C signals was increased by a factor of greater than 4 due to the combined effects of NOE and proton decoupling. The 7 T 13C MRS technique used decoupling power and average transmit power of less than 35 watts (W) and 3.6 W, respectively. Conclusion In vivo 13C MRS studies of human brain can be performed at 7 T, well below the RF safety threshold, by detecting carboxylic/amide carbons with broadband stochastic proton decoupling.