Mark Mikkelsen1,2, Steve C. N. Hui1,2, and Richard A. E. Edden1,2
1Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States, 2F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
1Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States, 2F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
We implemented a novel spectral registration (SR) approach for real-time B0 frequency correction for GABA-edited MRS. SR allows for full shot-to-shot, voxel-localized center frequency updates without the need for separate image-based navigators. Proof-of-concept results are presented.
Figure 1. Schematic of interleaved water referencing (IWR) and spectral registration (SR) for real-time center frequency (F0) updating of MEGA-PRESS acquisitions. IWR and acquisition of the SR reference, Sref(t), occur every ith and ith + 1 TRs, depending on the desired number of unsuppressed water reference acquisitions. For example, for a MEGA-PRESS scan with 320 water-suppressed averages and 8 unsuppressed water references, IWR will occur every 40th TR. OVS, outer-volume saturation; WS, water suppression.
Figure 2. Phantom experimental results. Top row: Relative changes in center frequency (ΔF0) over each of the four ~5-min GABA-edited MEGA-PRESS scans before and after an ~8-min EPI scan with and without interleaved water referencing (IWR) and spectral registration (SR). Bottom row: GABA-edited difference spectra for each of the four scans. The corresponding SNR of the 3.0 ppm edited GABA signal is shown.
