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.
