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Separate N‐acetyl aspartyl glutamate, N‐acetyl aspartate, aspartate, and glutamate quantification after pediatric mild traumatic brain injury in the acute phase
Author(s) -
Menshchikov Petr,
Ivantsova Anna,
Manzhurtsev Andrei,
Ublinskiy Maxim,
Yakovlev Alexey,
Melnikov Ilya,
Kupriyanov Dmitrii,
Akhadov Tolib,
Semenova Natalia
Publication year - 2020
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.28332
Subject(s) - glutamate receptor , traumatic brain injury , medicine , glutamate carboxypeptidase ii , chemistry , receptor , endocrinology , psychiatry , prostate , cancer
Purpose To separately measure N‐acetyl aspartul glutamate (NAAG), N‐acetyl aspartate (NAA), aspartate (Asp), and glutamate (Glu) concentrations in white matter (WM) using J‐editing techniques in patients with mild traumatic brain injury (mTBI) in the acute phase. Methods Twenty‐four patients with closed concussive head injury and 29 healthy volunteers were enrolled in the current study. For extended 1 H MRS examination, patients and controls were equally divided into two subgroups. In subgroup 1 (12 patients/15 controls), NAAG and NAA concentrations were measured in WM separately with MEGA‐PRESS (echo time/repetition time [TE/TR] = 140/2000 ms; δ ON NAA / δ OFF NAA = 4.84/4.38 ppm, δ ON NAAG / δ OFF NAAG = 4.61/4.15 ppm). In subgroup 2 (12 patients/14 controls), Asp and Glu concentrations were acquired with MEGA‐PRESS (TE/TR = 90/2000 ms; δ ON Asp / δ OFF Asp = 3.89/5.21 ppm) and TE‐averaged PRESS (TE from 35 ms to 185 ms with 2.5‐ms increments; TR = 2000 ms) pulse sequences, respectively. Results tNAA and NAAG concentrations were found to be reduced, while NAA concentrations were unchanged, after mild mTBI. Reduced Asp and elevated myo‐inositol (mI) concentrations were also found. Conclusion The main finding of the study is that the tNAA signal reduction in WM after mTBI is associated with a decrease in the NAAG concentration rather than a decrease in the NAA concentration, as was thought previously. This finding highlights the importance of separating these signals, at least for WM studies, to avoid misinterpretation of the results. NAAG plays an important role in selectively activating mGluR3 receptors, thus providing neuroprotective and neuroreparative functions immediately after mTBI. NAAG shows potential for the development of new therapeutic strategies for patients with injuries of varying severity.