High resolution spectroscopic imaging of GABA at 3 Tesla

A spin echo‐based MRSI sequence was developed to acquire edited spectra of γ‐aminobutyric acid in an entire slice. Water and lipid signals were suppressed by a dual‐band presaturation sequence, which included integrated outer volume suppression pulses for additional lipid suppression. Experiments in three normal volunteers were performed at 3 T using a 32‐channel head coil. High signal‐to‐noise ratio spectra and metabolic images of γ‐aminobutyric acid were acquired from nominal 4.5 cm 3 voxels (estimated actual voxel size 7.0 cm 3 ) in a scan time of 17 min. The sequence is also expected to co‐edit homocarnosine and macromolecules, giving a composite γ‐aminobutyric acid + resonance. The γ‐aminobutyric acid + to water ratio was measured using a companion water MRSI scan and was found to correlate linearly with the % gray matter (GM) of each voxel (γ‐aminobutyric acid + /water = (1.5 × GM + 3.2) × 10 −5 , R = 0.27), with higher γ‐aminobutyric acid + levels in gray matter compared with white. In conclusion, high signal‐to‐noise ratio γ‐aminobutyric acid‐MRSI is possible at 3 T within clinically feasible scan times. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.