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In vivo free induction decay based 3D multivoxel longitudinal hadamard spectroscopic imaging in the human brain at 3 T
Author(s) -
Tal Assaf,
Goelman Gadi,
Gonen Oded
Publication year - 2013
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.24327
Subject(s) - imaging phantom , physics , hadamard transform , nuclear magnetic resonance , free induction decay , fourier transform , voxel , spins , signal (programming language) , pulse sequence , spin echo , computer science , algorithm , optics , magnetic resonance imaging , artificial intelligence , quantum mechanics , medicine , radiology , programming language , condensed matter physics
We propose and demonstrate a full 3D longitudinal Hadamard spectroscopic imaging scheme for obtaining chemical shift maps, using adiabatic inversion pulses to encode the spins' positions. The approach offers several advantages over conventional Fourier‐based encoding methods, including a localized point spread function; no aliasing, allowing for volumes of interest smaller than the object being imaged; an option for acquiring noncontiguous voxels; and inherent outer volume rejection. The latter allows for doing away with conventional outer volume suppression schemes, such as point resolved spectroscopy (PRESS) and stimulated echo acquisition mode (STEAM), and acquiring non‐spin‐echo spectra with short acquisition delay times, limited only by the excitation pulse's duration. This, in turn, minimizes T 2 decay, maximizes the signal‐to‐noise ratio, and reduces J‐coupling induced signal decay. Results are presented for both a phantom and an in vivo healthy volunteer at 3 T. Magn Reson Med 69:903–911, 2013. © 2012 Wiley Periodicals, Inc.