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Abstract #1402

Quantitative Measurement of N-Acetylaspartyl Glutamate (NAAG) at 3 Tesla using TE-Averaged PRESS Spectroscopy & Lineshape Deconvolution

Yan Zhang1, Shizhe Li1, Christine Rebsch1, Stefano Marenco1, Jun Shen1

1National Institute of Mental Health, Bethesda, MD, United States

This abstract introduces a method whereby TE-averaged PRESS spectroscopy is used in conjunction with regularized lineshape deconvolution to measure N-acetyl-aspartyl-glutamate (NAAG). Averaging different echo times suppressed the signals of strongly-coupled multiple resonance lines near 2 ppm, including the signals of glutamate and the macromolecule MM20. The signal distortions were corrected by using lineshape deconvolution, and Tikhonov regularization was introduced to reduce the noise amplification arising from the deconvolution; as a result, spectral resolution could be enhanced without significantly sacrificing signal-to-noise ratio (SNR). The acetyl proton signal of NAAG was directly quantified by fitting the deconvoluted spectra, from 1.8 to 2.2 ppm, with a model that consisted of two Voigt-type lineshape peaks, yielding the NAAG-NAA ratio.