Sensitivity‐enhanced 13 C MR spectroscopy of the human brain at 3 Tesla

A new coil design for sensitivity‐enhanced 13 C MR spectroscopy (MRS) of the human brain is presented. The design includes a quadrature transmit/receive head coil optimized for 13 C MR sensitivity. Loss‐less blocking circuits inside the coil conductors allow this coil to be used inside a homogeneous circularly polarized 1 H B 1 field for 1 H decoupled 13 C MRS. A quadrature 1 H birdcage coil optimized for minimal local RF heating makes broadband 1 H decoupling in the entire human brain possible at 3 Tesla while remaining well within international safety guidelines for RF absorption. Apart from a substantial increase in sensitivity compared to conventional small linear coils, the quadrature 13 C coil combined with the quadrature 1 H birdcage coil allows efficient cross polarization (CP) in the brain, resulting in an additional 3.5‐fold sensitivity improvement compared to direct 13 C measurements without nuclear Overhauser enhancement (NOE) or polarization transfer. Combined with the gain in power efficiency, this setup allows broadband 1 H to 13 C CP over large areas of the brain. Clear 13 C resonances from glutamate (Glu), glutamine (Gln), aspartate (Asp), lactate (Lac), and γ‐aminobutyrate (GABA) carbon spins in the human brain demonstrate the quality of 13 C MR spectra obtained in vivo with this coil setup. Magn Reson Med, 2006. © 2005 Wiley‐Liss, Inc.