γ‐aminobutyric acid measurement in the human brain at 7 T: Short echo‐time or Mescher–Garwood editing

Lim, Song-I; Xin, Lijing

doi:10.1002/nbm.4706

Cited by 9 publications

(12 citation statements)

References 71 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…E ects on GABA/creatine ratio Measuring GABA using 1 H-MRS is challenging due to the low concentration of GABA in the brain and the spectral overlap with other metabolites. Thus, GABA levels should be interpreted with caution, unless measured at higher magnetic field strength (≥7 T MRS) or special sequences (74). Even though we found a significant increase of GABA/creatine ratio in group IEU, the median relative CRLB were high, so the current results should be interpreted with care.…”

Section: E Ects On Glucose/creatine Ratiomentioning

confidence: 58%

Ketamine administration in idiopathic epileptic and healthy control dogs: Can we detect differences in brain metabolite response with spectroscopy?

Wieser

Beckmann²,

Kutter³

et al. 2023

Front. Vet. Sci.

View full text Add to dashboard Cite

IntroductionIn recent years ketamine has increasingly become the focus of multimodal emergency management for epileptic seizures. However, little is known about the effect of ketamine on brain metabolites in epileptic patients. Magnetic resonance spectroscopy (MRS) is a non-invasive technique to estimate brain metabolites in vivo. Our aim was to measure the effect of ketamine on thalamic metabolites in idiopathic epileptic (IE) dogs using 3 Tesla MRS. We hypothesized that ketamine would increase the glutamine—glutamate (GLX)/creatine ratio in epileptic dogs with and without antiseizure drug treatment, but not in control dogs. Furthermore, we hypothesized that no different responses after ketamine administration in other measured brain metabolite ratios between the different groups would be detected.MethodsIn this controlled prospective experimental trial IE dogs with or without antiseizure drug treatment and healthy client-owned relatives of the breeds Border Collie and Greater Swiss Mountain Dog, were included. After sedation with butorphanol, induction with propofol and maintenance with sevoflurane in oxygen and air, a single voxel MRS at the level of the thalamus was performed before and 2 min after intravenous administration of 1 mg/kg ketamine. An automated data processing spectral fitting linear combination model algorithm was used to estimate all commonly measured metabolite ratios. A mixed ANOVA with the independent variables ketamine administration and group allocation was performed for all measured metabolites. A p < 0.05 was considered statistically significant.ResultsTwelve healthy control dogs, 10 untreated IE and 12 treated IE dogs were included. No significant effects for GLX/creatine were found. However, increased glucose/creatine ratios were found (p < 0.001) with no effect of group allocation. Furthermore, increases in the GABA/creatine ratio were found in IEU dogs.DiscussionMRS was able to detect changes in metabolite/creatine ratios after intravenous administration of 1 mg/kg ketamine in dogs and no evidence was found that excitatory effects are induced in the thalamus. Although it is beyond the scope of this study to investigate the antiseizure potential of ketamine in dogs, results of this research suggest that the effect of ketamine on the brain metabolites could be dependent on the concentrations of brain metabolites before administration.

show abstract

Section: E Ects On Glucose/creatine Ratiomentioning

confidence: 58%

Ketamine administration in idiopathic epileptic and healthy control dogs: Can we detect differences in brain metabolite response with spectroscopy?

Wieser

Beckmann²,

Kutter³

et al. 2023

Front. Vet. Sci.

View full text Add to dashboard Cite

show abstract

“…Therefore, besides employing the editing method that facilitates the separation of GABA from other metabolites and achieves good measurement reproducibility, our study highlights the potential for achieving this goal by optimizing the basis‐set approach with the short‐TE method. The results revealed that, in mPFC, the CV of GABA using sSPECIAL combined with the LM approach can be reduced to a similar level compared with those provided by the MEGA‐sSPECIAL method 35 . Furthermore, the optimization of GABA spin parameters plays a crucial role in achieving accurate fitting and quantification.…”

Section: Discussionmentioning

confidence: 94%

“…The homogeneities of the static magnetic field were optimized with the FASTMAP shimming method 32,33 . The 1 H MR spectra were acquired using semi‐adiabatic spin‐echo full‐intensity‐acquired localization (sSPECIAL) 9 (TR/TE = 4000/16 ms, bandwidth = 4 kHz, 4096 datapoints) from the thalamus ( n = 3, 120 averages, voxel size = 20 × 18 × 16 mm 3 ), 34 the primary motor cortex (M1) ( n = 5, 128 averages, voxel size = 30 × 20 × 20 mm 3 ), and the mPFC ( n = 3, 128 averages, voxel size = 30 × 20 × 20 mm 3 ) 35 . The outer volume suppression was interleaved with VAPOR water suppression 36 .…”

Section: Methodsmentioning

confidence: 99%

“…32,33 The 1 H MR spectra were acquired using semi-adiabatic spin-echo full-intensity-acquired localization (sSPECIAL) 9 (TR/TE = 4000/16 ms, bandwidth = 4 kHz, 4096 datapoints) from the thalamus (n = 3, 120 averages, voxel size = 20 Â 18 Â 16 mm 3 ), 34 the primary motor cortex (M1) (n = 5, 128 averages, voxel size = 30 Â 20 Â 20 mm 3 ), and the mPFC (n = 3, 128 averages, voxel size = 30 Â 20 Â 20 mm 3 ). 35 The outer volume suppression was interleaved with VAPOR water suppression. 36 The unsuppressed water spectra were acquired by the same protocol by turning off the water suppression RF pulses.…”

Section: H Mr Spectroscopymentioning

confidence: 99%

See 1 more Smart Citation

Improved reproducibility of γ‐aminobutyric acid measurement from short‐echo‐time proton MR spectroscopy by linewidth‐matched basis sets in LCModel

Xiao,

Lanz,

Lim

et al. 2023

NMR in Biomedicine

Self Cite

View full text Add to dashboard Cite

Abstractγ‐Aminobutyric acid (GABA), as the primary inhibitory neurotransmitter, is extremely important for maintaining healthy brain function, and deviations from GABA homeostasis are related to various brain diseases. Short‐echo‐time (short‐TE) proton MR spectroscopy (1H‐MRS) has been employed to measure GABA concentration from various human brain regions at high magnetic fields. The aim of this study was to investigate the effect of spectral linewidth on GABA quantification and explore the application of an optimized basis‐set preparation approach using a spectral‐linewidth‐matched (LM) basis set in LCModel to improve the reproducibility of GABA quantification from short‐TE 1H‐MRS. In contrast to the fixed‐linewidth basis‐set approach, the LM basis‐set preparation approach, where all metabolite basis spectra were simulated with a linewidth 4 Hz narrower than that of water, showed a smaller standard deviation of estimated GABA concentration from synthetic spectra with varying linewidths and lineshapes. The test–retest reproducibility was assessed by the mean within‐subject coefficient of variation, which improved from 19.2% to 12.0% in the thalamus, from 27.9% to 14.9% in the motor cortex, and from 9.7% to 2.8% in the medial prefrontal cortex using LM basis sets at 7 T. We conclude that spectral linewidth has a large effect on GABA quantification from short‐TE 1H‐MRS data and that using LM basis sets in LCModel can improve the reproducibility of GABA quantification.

show abstract

“…This limitation is partially due to the much lower GABA concentration in comparison with other brain metabolites and the GABA is obscured by signals from more abundant metabolites. Measurements at higher magnetic field strengths and dedicated sequences could help to overcome this technical issue ( 52 ).…”

Section: Discussionmentioning

confidence: 99%

Single-Voxel Proton Magnetic Resonance Spectroscopy of the Thalamus in Idiopathic Epileptic Dogs and in Healthy Control Dogs

Mauri

Richter²,

Steffen³

et al. 2022

Front. Vet. Sci.

View full text Add to dashboard Cite

The role of magnetic resonance spectroscopy (MRS) in the investigation of brain metabolites in epileptic syndromes in dogs has not been explored systematically to date. The aim of this study was to investigate metabolites in the thalamus in dogs affected by idiopathic epilepsy (IE) with and without antiepileptic drug treatment (AEDT) and to compare them to unaffected controls. Our hypothesis is that similar to humans with generalized epilepsy and loss of consciousness, N-acetyl aspartate (NAA) would be reduced, and glutamate–glutamine (Glx) would be increased in treated and untreated IE in comparison with the control group. In this prospective case–control study, Border Collie (BC) and Greater Swiss Mountain dog (GSMD) were divided into three groups: (1) healthy controls, IE with generalized tonic–clonic seizures with (2) and without (3) AEDT. A total of 41 BC and GSMD were included using 3 Tesla single-voxel proton MRS of the thalamus (PRESS localization, shortest TE, TR = 2000 ms, NSA = 240). After exclusion of 11 dogs, 30 dogs (18 IE and 12 healthy controls) remained available for analysis. Metabolite concentrations were estimated with LCModel using creatine as reference and compared using Kruskal–Wallis and Wilcoxon rank-sum tests. The Kruskal–Wallis test revealed significant differences in the NAA-to-creatine (p = 0.04) and Glx-to-creatine (p = 0.03) ratios between the three groups. The Wilcoxon rank-sum test further showed significant reduction in the NAA/creatine ratio in idiopathic epileptic dogs under AEDT compared to epileptic dogs without AEDT (p = 0.03) and compared to healthy controls (p = 0.03). In opposite to humans, Glx/creatine ratio was significantly reduced in dogs with IE under AEDT compared to epileptic dogs without AEDT (p = 0.03) and controls (p = 0.02). IE without AEDT and healthy controls did not show significant difference, neither in NAA/creatine (p = 0.60), nor in Glx-to-creatine (p = 0.55) ratio. In conclusion, MRS showed changes in dogs with IE and generalized seizures under AEDT, but not in those without AEDT. Based upon these results, MRS can be considered a useful advanced imaging technique for the evaluation of dogs with IE in the clinical and research settings.

show abstract

γ‐aminobutyric acid measurement in the human brain at 7 T: Short echo‐time or Mescher–Garwood editing

Cited by 9 publications

References 71 publications

Ketamine administration in idiopathic epileptic and healthy control dogs: Can we detect differences in brain metabolite response with spectroscopy?

Ketamine administration in idiopathic epileptic and healthy control dogs: Can we detect differences in brain metabolite response with spectroscopy?

Improved reproducibility of γ‐aminobutyric acid measurement from short‐echo‐time proton MR spectroscopy by linewidth‐matched basis sets in LCModel

Single-Voxel Proton Magnetic Resonance Spectroscopy of the Thalamus in Idiopathic Epileptic Dogs and in Healthy Control Dogs

Contact Info

Product

Resources

About