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Fast proton spectroscopic imaging employing k ‐space weighting achieved by variable repetition times
Author(s) -
Kühn Bernd,
Dreher Wolfgang,
Norris David G.,
Leibfritz Dieter
Publication year - 1996
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.1910350403
Subject(s) - sinc function , k space , apodization , flip angle , signal to noise ratio (imaging) , weighting , optics , signal (programming language) , physics , noise (video) , nuclear magnetic resonance , noise reduction , algorithm , point spread function , mathematics , computer science , fourier transform , magnetic resonance imaging , mathematical analysis , artificial intelligence , acoustics , medicine , image (mathematics) , radiology , programming language
Abstract A k ‐space weighted spectroscopic imaging (SI) method is presented that allows a reduction in the total data acquisition time by up to 55% compared with standard SI. The k ‐space weighting is achieved by varying the repetition time, thus realizing an inherent apodization that corresponds to a circularly symmetric generalized Hamming filter. The flip angle is varied with the repetition time to enhance the signal‐to‐noise ratio. These techniques were employed using a short echo time of 10 ms. In vivo measurements on healthy rat brain at 4.7 T were conducted, obtaining two‐dimensional spectroscopic imaging data from a 25 × 25 circularly reduced k ‐space area in as little as 5 min. The signal‐to‐noise ratio is sufficiently high to detect J ‐coupled resonances such as myo ‐inositol or glutamate/glutamine, demonstrating the ability to combine short acquisition times with comprehensive metabolic information. The T 1 dependency of the apodization and the corresponding point spread function was evaluated by computer simulations. The achievable signal‐to‐noise ratio per unit time was compared with standard SI giving a parameter‐dependent advantage of approximately 20% of the standard SI method.