title: Highly resolved two-dimensional ¹H spectroscopy of the human brain using ISIS CT-PRESS with resolution enhancement.
abstract: In constant time (CT) point-resolved spectroscopy (PRESS), echo centers shift with the fast decay of short T₂* on two-dimensional (2D) time domain (TD) data under inhomogeneous B₀ field like in vivo conditions. Though ¹H decoupling along the F₁ direction is a feature of this method, the tilted and broadened peak pattern on the F₁-F₂ plane after reconstruction causes the peaks to overlap. To enhance resolution to achieve highly resolved 2D CT-PRESS spectra in the human brain, we propose a 2-part window function that comprises an enhancement part for shifting echoes with fast decay and a conventional part, such as Lorentzian, Gaussian, or sine-bell function. We obtained 2D spectra from human brains at 4.7T. The 3 diagonal peaks of C4H of glutamate (Glu C4H) at 2.35 ppm, C2H of γ-amino butyric acid (GABA C2H) at 2.28 ppm, and C4H of glutamine (Gln C4H) at 2.44 ppm-overlapped on the spectra processed with the conventional window but clearly resolved on the spectra using the proposed enhancement window. The signal-to-noise ratio per unit measurement time of Glu C4H on a CT-PRESS spectrum of the human brain was 1.7 times higher than that on a spectrum obtained by CT-correlation spectroscopic (COSY). In conclusion, 2D CT-PRESS spectra processed with the proposed window function to enhance resolution can resolve peaks of coupled ¹H spins with higher accuracy and sensitivity.
authors.affiliation: Center for Environmental Measurement and Analysis, National Institutes for Environmental Studies, Tsukuba, Ibaraki, Japan. idewata@nies.go.jp
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Watanabe
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Takaya
authors.forename: Fumiyuki
authors.initials: F
authors.lastname: Mitsumori
mesh_terms: D001921:Brain / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D005973:Glutamine; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid