Table 3.

Summary of metabolite changes following traumatic brain injury (TBI) detectable with in vivo ³¹P MRS.

	Changes in hyperacute stagea	Changes in subacute stage	Correlation to prognosis
Metabolites associated with energy metabolism	↓ PCr	↑ PCr/ATP
	↑ Pi
	↓ PCr/Pi	↑ PCr/Pi	✓✽
Change in pH	↓		✓
Mg2+	↓†	↑↓	✓✽†

PCr, phosphocreatine; Pi, inorganic phosphate; ATP, adenosine triphosphate.

↑: increase in metabolite; ↓: decrease in metabolite; ✓: potential clinical use as a prognostic predictor.

^✽Animal studies.

^†In animal studies, Mg²⁺ falls proportionally to injury severity, except for following the most severe TBI.