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Whole-Brain N-Acetylaspartate Concentration Is Preserved during Mild Hypercapnia Challenge.

Publication ,  Journal Article
Chawla, S; Ge, Y; Lu, H; Marshall, O; Davitz, MS; Fatterpekar, G; Soher, BJ; Gonen, O
Published in: AJNR Am J Neuroradiol
November 2015

BACKGROUND AND PURPOSE: Although NAA is often used as a marker of neuronal health and integrity in neurologic disorders, its normal response to physiologic challenge is not well-established and its changes are almost always attributed exclusively to brain pathology. The purpose of this study was to test the hypothesis that the neuronal cell marker NAA, often used to assess neuronal health and integrity in neurologic disorders, is not confounded by (possibly transient) physiologic changes. Therefore, its decline, when observed by using (1)H-MR spectroscopy, can almost always be attributed exclusively to brain pathology. MATERIALS AND METHODS: Twelve healthy young male adults underwent a transient hypercapnia challenge (breathing 5% CO2 air mixture), a potent vasodilator known to cause a substantial increase in CBF and venous oxygenation. We evaluated their whole-brain NAA by using nonlocalizing proton MR spectroscopy, venous oxygenation with T2-relaxation under spin-tagging MR imaging, CBF with pseudocontinuous arterial spin-labeling, and the cerebral metabolic rate of oxygen, during normocapnia (breathing room air) and hypercapnia. RESULTS: There was insignificant whole-brain NAA change (P = .88) from normocapnia to hypercapnia and back to normocapnia in this cohort, as opposed to highly significant increases: 28.0 ± 10.3% in venous oxygenation and 49.7 ± 16.6% in global CBF (P < 10(-4)); and a 6.4 ± 10.9% decrease in the global cerebral metabolic rate of oxygen (P = .04). CONCLUSIONS: Stable whole-brain NAA during normocapnia and hypercapnia, despite significant global CBF and cerebral metabolic rate of oxygen changes, supports the hypothesis that global NAA changes are insensitive to transient physiology. Therefore, when observed, they most likely reflect underlying pathology resulting from neuronal cell integrity/viability changes, instead of a response to physiologic changes.

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Published In

AJNR Am J Neuroradiol

DOI

EISSN

1936-959X

Publication Date

November 2015

Volume

36

Issue

11

Start / End Page

2055 / 2061

Location

United States

Related Subject Headings

  • Young Adult
  • Nuclear Medicine & Medical Imaging
  • Male
  • Magnetic Resonance Spectroscopy
  • Hypercapnia
  • Humans
  • Brain Chemistry
  • Brain
  • Aspartic Acid
  • Adult
 

Citation

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Chawla, S., Ge, Y., Lu, H., Marshall, O., Davitz, M. S., Fatterpekar, G., … Gonen, O. (2015). Whole-Brain N-Acetylaspartate Concentration Is Preserved during Mild Hypercapnia Challenge. AJNR Am J Neuroradiol, 36(11), 2055–2061. https://doi.org/10.3174/ajnr.A4424
Chawla, S., Y. Ge, H. Lu, O. Marshall, M. S. Davitz, G. Fatterpekar, B. J. Soher, and O. Gonen. “Whole-Brain N-Acetylaspartate Concentration Is Preserved during Mild Hypercapnia Challenge.AJNR Am J Neuroradiol 36, no. 11 (November 2015): 2055–61. https://doi.org/10.3174/ajnr.A4424.
Chawla S, Ge Y, Lu H, Marshall O, Davitz MS, Fatterpekar G, et al. Whole-Brain N-Acetylaspartate Concentration Is Preserved during Mild Hypercapnia Challenge. AJNR Am J Neuroradiol. 2015 Nov;36(11):2055–61.
Chawla, S., et al. “Whole-Brain N-Acetylaspartate Concentration Is Preserved during Mild Hypercapnia Challenge.AJNR Am J Neuroradiol, vol. 36, no. 11, Nov. 2015, pp. 2055–61. Pubmed, doi:10.3174/ajnr.A4424.
Chawla S, Ge Y, Lu H, Marshall O, Davitz MS, Fatterpekar G, Soher BJ, Gonen O. Whole-Brain N-Acetylaspartate Concentration Is Preserved during Mild Hypercapnia Challenge. AJNR Am J Neuroradiol. 2015 Nov;36(11):2055–2061.

Published In

AJNR Am J Neuroradiol

DOI

EISSN

1936-959X

Publication Date

November 2015

Volume

36

Issue

11

Start / End Page

2055 / 2061

Location

United States

Related Subject Headings

  • Young Adult
  • Nuclear Medicine & Medical Imaging
  • Male
  • Magnetic Resonance Spectroscopy
  • Hypercapnia
  • Humans
  • Brain Chemistry
  • Brain
  • Aspartic Acid
  • Adult