Dual-volume excitation and parallel reconstruction for J-difference-edited MR spectroscopy

To develop J-difference editing with parallel reconstruction in accelerated multivoxel (PRIAM) for simultaneous measurement in two separate brain regions of γ-aminobutyric acid (GABA) or glutathione.

PRIAM separates signals from two simultaneously excited voxels using receiver-coil sensitivity profiles. PRIAM was implemented into Mescher-Garwood (MEGA) edited experiments at 3 Tesla (T), and validated by acquiring dual-voxel MEGA-PRIAM (and compared with conventional single-voxel MEGA-PRESS) spectra from a GABA/glutathione phantom, and 11 healthy participants.

MEGA-PRIAM effectively separated phantom spectra with ∼3-4% between-voxel contamination. GABA and glutathione measurements agreed well with those obtained using single-voxel MEGA-PRESS (mean difference was below 2% in GABA levels, and below 7% in glutathione levels). In vivo, GABA- and glutathione-edited spectra were successfully reconstructed with a mean in vivo g-factor of 1.025 (typical voxel-center separation: 7-8 cm). MEGA-PRIAM experiments showed higher signal-to-noise ratio than sequential single-voxel experiments of the same total duration (mean improvement 1.38 ± 0.24).

Simultaneous acquisition of J-difference-edited GABA or glutathione spectra from two voxels is feasible at 3 T. MEGA-PRIAM increases data acquisition rates compared with MEGA-PRESS by a factor of 2. Magn Reson Med, 2016. © 2016 International Society for Magnetic Resonance in Medicine.