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A new method for fast proton spectroscopic imaging: Spectroscopic GRASE
Author(s) -
Dreher Wolfgang,
Leibfritz Dieter
Publication year - 2000
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 - 10.1002/1522-2594(200011)44:5<668::aid-mrm2>3.0.co;2-a
Subject(s) - homonuclear molecule , pulse sequence , nuclear magnetic resonance , excitation , chemistry , analytical chemistry (journal) , spin echo , proton , physics , magnetic resonance imaging , molecule , medicine , organic chemistry , quantum mechanics , chromatography , radiology
A new fast spectroscopic imaging method is presented which allows both a very short minimum total measurement time and effective homonuclear decoupling. After each excitation, all data points from N GE k x ‐k y ‐slices at different k ω ‐values are acquired by using a gradient and spin echo (GRASE) imaging sequence. The delay between consecutive gradient echoes, which are measured with uniform phase encoding between consecutive refocusing α‐pulses, is the inverse of the spectral width (SW). A refocusing 180° pulse, which is applied within a constant delay between excitation and the GRASE sequence, is shifted in a series of measurements by an increment N GE /(2 • SW) to cover the whole k ω ‐k x ‐k y ‐space. Spectroscopic GRASE was implemented on a 4.7 T imaging system and tested on phantoms and normal rat brain in vivo. Measurements were performed with a nominal voxel size of 1.5 × 1.5 × 3 mm 3 and a spatial 64 × 64 matrix. The total measurement time was 2 or 4 min using a repetition time of 1.9 sec, 96 chemical shift encoding steps, SW = 800 Hz, N GE = 3, and 2 or 4 accumulations. Magn Reson Med 44:668–672, 2000. © 2000 Wiley‐Liss, Inc.