Table 2 Typical metabolites examined in neurological ¹H magnetic resonance spectroscopy [[13]]

Lipid

0.9-1.5

Not usually visible in MRS unless released by pathological process such as trauma

Lactate

1.3

End product of anaerobic glycolysis. Indicator of hypoxia and impairment of perfusion

N-acetyl aspartate (NAA)

2.0

Synthesized in neurons. Marker of neuronal viability

Glutamate/glutamine (Glx)

2.2-2.5

Glutamate is the primary excitatory neurotransmitter in the brain. Glutamine is found in astrocytes. Glx may be predictive of outcome after severe TBI and associated with immunoexcitotoxicity or secondary dysfunction

Choline (Cho)

3.2

Membrane marker. Elevated in cases of high membrane turnover. May indicate diffuse axonal injury

Myo-inositol (mI)

3.5

Astrocyte marker and osmolyte. Involved in the metabolism of phosphatidyl inositol (a membrane phospholipid) - expected to increase after TBI due to membrane damage. May also be a glial marker

Creatine (Cr)

3.0

Found in metabolic active tissues, used in energy storage and transfer. Used as an internal standard for other metabolites (for example, NAA/Cr, Cho/Cr)