Proton spectroscopy without water suppression: The oversampled J‐resolved experiment

Abstract

A method is introduced for obtaining proton spectra in vivo with all the advantages of a full water signal. The method, based on F1 oversampled J-resolved spectroscopy, makes it possible to separate metabolite signals from unwanted baseline artifacts. The dominant water resonance is used as a 2D reference signal for the phase-sensitive reconstruction of the 2D J-resolved metabolite spectra. The powerful specificity of this method is demonstrated with model compound spectra, phantoms, and in vivo examples.

Restoration of motion‐related signal loss and line‐shape deterioration of proton MR spectra using the residual water as intrinsic reference

“…Adjustment of the residual water resonance to 10 -20 times the metabolite peaks was a compromise between retaining sufficient water signal and avoiding baseline distortions of the spectrum and spurious water sidebands (18). Thus, the method performs worse for small VOIs, where a reasonable trade-off is more difficult to achieve.…”

Development and Resolution of Brain Lesions Caused by Pyrithiamine- and Dietary-Induced Thiamine Deficiency and Alcohol Exposure in the Alcohol-Preferring Rat: A Longitudinal Magnetic Resonance Imaging and Spectroscopy Study

“…Single-voxel two-dimensional (2D) J-resolved MRS spectra were acquired, using 4.7 min acquisitions (Dreher and Leibfritz, 1995;Hurd et al, 1998) (TE1/TR ¼ 35/2000 ms, DTE ¼ 10 ms, 16 TE steps, eight averages per TE step) repeated four times with water suppression and once without water suppression. Water suppression was performed with CHESS (Haase et al, 1985), with flip angles determined by the default GE PRESS sequence.…”

Localized Proton Spectroscopy without Water Suppression: Removal of Gradient Induced Frequency Modulations by Modulus Signal Selection

“…[2] and Eq. [3], the term ω G (t) produces a group of symmetric peaks (sidebands) for each signal component. The magnitudes of these sidebands depend on the amplitude as well as the amplitude…”

“…It can also be used for corrections of lineshape distortions as well as intervoxel frequency shifts adjustments (2). However, these localized MR spectra acquired without solvent suppression can exhibit an ensemble of spurious peaks added to the metabolite resonances (3). According to the literature, the origin of these spurious peaks, called sidebands, might be the vibrations of the gradients at acoustic frequencies during data acquisition (4), the oscillation of the magnetic field ( ) (5), or a correlation between both gradient-induced acoustic vibrations and the oscillation of the ( ) field (6).…”

“…Hurd et al have proposed an over-sampled PRESS-localized 2D J-resolved experiment to eliminate these distortions (3). However, this solution is time consuming and can limit the minimum TE possible in localized MRS techniques.…”