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Volumetric spectroscopic imaging with spiral‐based k ‐space trajectories
Author(s) -
Adalsteinsson Elfar,
Irarrazabal Pablo,
Topp Simon,
Meyer Craig,
Macovski Albert,
Spielman Daniel M.
Publication year - 1998
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910390606
Subject(s) - spiral (railway) , k space , signal (programming language) , nuclear magnetic resonance , fourier transform , pixel , physics , bandwidth (computing) , signal to noise ratio (imaging) , voxel , attenuation , optics , materials science , computer science , artificial intelligence , mathematics , mathematical analysis , quantum mechanics , programming language , computer network
Spiral‐based k ‐space trajectories were applied in a spectroscopic imaging sequence with time‐varying readout gradients to collect volumetric chemical shift information. In addition to spectroscopic imaging of low signal‐to‐noise ratio (SNR) brain metabolites, the spiral trajectories were used to rapidly collect reference signals from the high SNR water signal to automatically phase the spectra and to aid the reconstruction of metabolite maps. Spectral‐spatial pulses were used for excitation and water suppression. The pulses were designed to achieve stable phase profiles in the presence of up to 20% variation in the radiofrequency field. A gridding algorithm was used to resample the data onto a rectilinear grid before fast Fourier transforms. This method was demonstrated by in vivo imaging of brain metabolites at 1.5 T with 10 slices of 18 × 18 pixels each. Nominal voxel size was 1.1 cc, spectral bandwidth was 400 Hz, scan time was 18 min for the metabolite scan and 3 min for the reference scan.