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N‐acetyl‐aspartyl‐glutamate detection in the human brain at 7 Tesla by echo time optimization and improved Wiener filtering
Author(s) -
An Li,
Li Shizhe,
Wood Emily T.,
Reich Daniel S.,
Shen Jun
Publication year - 2014
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.25007
Subject(s) - wiener filter , deconvolution , signal (programming language) , wiener deconvolution , distortion (music) , spectral resolution , multiplet , nuclear magnetic resonance , chemistry , computer science , spectral line , biological system , algorithm , physics , blind deconvolution , telecommunications , biology , amplifier , bandwidth (computing) , astronomy , programming language
Purpose To report enhanced signal detection for measuring N‐acetyl‐aspartyl‐glutamate (NAAG) in the human brain at 7 Tesla by echo time (TE) ‐optimized point‐resolved spectroscopy (PRESS) and improved Wiener filtering. Methods Using a highly efficient in‐house developed numerical simulation program, a PRESS sequence with (TE 1 , TE 2 ) = (26, 72) ms was found to maximize the NAAG signals relative to the overlapping Glu signals. A new Wiener filtering water reference deconvolution method was developed to reduce broadening and distortions of metabolite peaks caused by B 0 inhomogeneity and eddy currents. Results Monte Carlo simulation results demonstrated that the new Wiener filtering method offered higher spectral resolution, reduced spectral artifacts, and higher accuracy in NAAG quantification compared with the original Wiener filtering method. In vivo spectra and point spread functions of signal distortion confirmed that the new Wiener filtering method lead to improved spectral resolution and reduced spectral artifacts. Conclusion TE‐optimized PRESS in combination with a new Wiener filtering method made it possible to fully use both the NAAG singlet signal at 2.05 ppm and the NAAG multiplet signal at 2.18 ppm in the quantification of NAAG. A more accurate characterization of lineshape distortion for Wiener filtering needs B 0 field maps and segmented anatomical images to exclude contribution from cerebral spinal fluid. Magn Reson Med 72:903–912, 2014. © 2013 Wiley Periodicals, Inc.