Short echo-time Magnetic Resonance Spectroscopy in ALS, simultaneous quantification of glutamate and GABA at 3 T

Sci Rep. 2019 Nov 26;9(1):17593. doi: 10.1038/s41598-019-53009-4.

Abstract

Cortical hyperexcitability has been found in early Amyotrophic Lateral Sclerosis (ALS) and is hypothesized to be a key factor in pathogenesis. The current pilot study aimed to investigate cortical inhibitory/excitatory balance in ALS using short-echo Magnetic Resonance Spectroscopy (MRS). Patients suffering from ALS were scanned on a 3 T Trio Siemens MR scanner using Spin Echo Full Intensity Acquired Localized (SPECIAL) Magnetic Resonance Spectroscopy in primary motor cortex and the occipital lobe. Data was compared to a group of healthy subjects. Nine patients completed the scan. MRS data was of an excellent quality allowing for quantification of a range of metabolites of interest in ALS. In motor cortex, patients had Glutamate/GABA and GABA/Cr- ratios comparable to healthy subjects. However, Glutamate/Cr (p = 0.002) and the neuronal marker N-acetyl-aspartate (NAA/Cr) (p = 0.034) were low, possibly due to grey-matter atrophy, whereas Glutathione/Cr (p = 0.04) was elevated. In patients, NAA levels correlated significantly with both hand strength (p = 0.027) and disease severity (p = 0.016). In summary SPECIAL MRS at 3 T allows of reliable quantification of a range of metabolites of interest in ALS, including both excitatory and inhibitory neurotransmitters. The method is a promising new technique as a biomarker for future studies on ALS pathophysiology and monitoring of disease progression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Amyotrophic Lateral Sclerosis / metabolism*
  • Amyotrophic Lateral Sclerosis / pathology
  • Amyotrophic Lateral Sclerosis / physiopathology
  • Aspartic Acid / analogs & derivatives
  • Aspartic Acid / analysis
  • Atrophy
  • Choline / analysis
  • Creatine / analysis
  • Disease Progression
  • Female
  • Glutamic Acid / analysis*
  • Glutamine / analysis
  • Glutathione / analysis
  • Gray Matter / pathology
  • Hand Strength
  • Humans
  • Inositol / analysis
  • Magnetic Resonance Spectroscopy / methods*
  • Male
  • Middle Aged
  • Motor Cortex / chemistry*
  • Motor Cortex / pathology
  • Occipital Lobe / chemistry*
  • Occipital Lobe / pathology
  • Pilot Projects
  • Severity of Illness Index
  • Single-Blind Method
  • gamma-Aminobutyric Acid / analysis*

Substances

  • Glutamine
  • Aspartic Acid
  • Glutamic Acid
  • Inositol
  • gamma-Aminobutyric Acid
  • N-acetylaspartate
  • Glutathione
  • Creatine
  • Choline