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Rapid multi‐echo measurement of brain metabolite T 2 values at 7 T using a single‐shot spectroscopic Carr–Purcell–Meiboom–Gill sequence and prior information
Author(s) -
Ronen Itamar,
Ercan Ece,
Webb Andrew
Publication year - 2013
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.2951
Subject(s) - amplitude , echo (communications protocol) , nuclear magnetic resonance , singular value decomposition , time domain , weighting , physics , chemistry , mathematics , algorithm , optics , computer science , acoustics , computer network , computer vision
We present a method for the robust and accurate estimation of brain metabolite transverse relaxation times ( T 2 ) from multiple spin‐echo data acquired with a single‐shot Carr–Purcell–Meiboom–Gill (CPMG) spectroscopic sequence. Each acquired echo consists of a small number of complex time‐domain data points. The amplitudes of the spectral components in each echo are calculated by solving a set of linear equations in which previously estimated frequencies and linewidths serve as prior information. These priors are obtained from a short MRS experiment in which a large number of time‐domain data points are acquired, and are subsequently estimated using linear prediction with singular value decomposition (LPSVD) processing. We show that this process can be used to accurately and rapidly measure the T 2 values for the main singlet resonances in single‐volume MRS measurements in the brain. The proposed method can be generalized to any set of MRS experiments comprising repeated measurements of amplitude changes, e.g. as a function of an experimental parameter, such as TE, inversion time or diffusion weighting. Copyright © 2013 John Wiley & Sons, Ltd.