Spectral editing in ¹H magnetic resonance spectroscopy: Experts' consensus recommendations

Abstract

Spectral editing in in vivo 1 H-MRS provides an effective means to measure lowconcentration metabolite signals that cannot be reliably measured by conventional MRS techniques due to signal overlap, for example, γ-aminobutyric acid, glutathione and D-2-hydroxyglutarate. Spectral editing strategies utilize known J-coupling relationships within the metabolite of interest to discriminate their resonances from overlying signals. This consensus recommendation paper provides a brief overview of commonly used homonuclear editing techniques and considerations for data acquisition, processing and quantification. Also, we have listed the experts' recommendations for minimum requirements to achieve adequate spectral editing and reliable quantification. These include selecting the right editing sequence, dealing with frequency drift, handling unwanted coedited resonances, spectral fitting of edited spectra, setting up multicenter clinical trials and recommending sequence parameters to be reported in publications.

Contribution of macromolecules to brain 1H MR spectra: Experts' consensus recommendations

“…MRS of GABA in vivo, the major inhibitory neurotransmitter, is technically challenging because of the presence of overlapping resonances from metabolites, such as creatine, glutamate/glutamine, GSH, homocarnosine and NAA. For this reason, spectral editing is employed for GABA detection, 90 including J-difference editing 91,92 and the doubly selective multiple quantum filtering method. 90,93 These methods exploit the Jcoupling of GABA β and γ methylene protons resonating at 1.9 and 3.0 ppm.…”

“…For this reason, spectral editing is employed for GABA detection, 90 including J-difference editing 91,92 and the doubly selective multiple quantum filtering method. 90,93 These methods exploit the Jcoupling of GABA β and γ methylene protons resonating at 1.9 and 3.0 ppm. However, because of the finite bandwidth of the frequency-selective editing pulse set at 1.9 ppm, the MM resonance at 1.7 ppm, which is coupled to the MM resonance at 3.0 ppm, is also partially inverted 3,4,8 (Figure 6), contributing to the net signal measured in the difference spectrum at 3.0 ppm.…”

Terminology and concepts for the characterization of in vivo MR spectroscopy methods and MR spectra: Background and experts' consensus recommendations

“…Hence, it is recommended to conceptually define editing efficiency as the ratio of the integral of absolute values under the edited resonances (with relaxation weighting removed) to the same measure of those resonances in a spectrum acquired with zero TE and an equal number of acquisitions as needed for the edited spectrum. To distinguish between the theoretical limits of an editing method and the editing efficiency for a specific implementation 67 (in terms of, eg, properties of the applied RF pulses for editing and localization) and experimental situation (eg, shim, field strength), it is proposed to distinguish between a theoretical and a practical editing efficiency.…”

Advanced single voxel 1H magnetic resonance spectroscopy techniques in humans: Experts' consensus recommendations

“…Note that edited MRS has been intentionally left out of this paper since it is covered in a separate contribution in this special issue. 3…”

“…We further provide recommendations to MR scanner vendors to enable users to acquire high quality MRS data at high and ultrahigh fields. Note that edited MRS has been intentionally left out of this paper since it is covered in a separate contribution in this special issue 3 …”