Serial changes in metabolism and histology in the cold-injury trauma rat brain model--proton magnetic resonance imaging and spectroscopy study.

The serial changes in metabolism and histology during the first 24 hours in the cold-injury trauma rat brain model were investigated by proton magnetic resonance (MR) imaging and high-resolution proton MR spectroscopy. Edema developed extensively via the corpus callosum in the ipsi- and contralateral hemispheres during observation as shown by gradually increased signal intensity on proton MR images. Proton MR spectroscopy showed increased levels of acetate (Ace), lactate (Lac), and glutamine (Glmi) 1 hour after lesion formation. The elevated Glmi level slightly decreased, the level of alanine (Ala) increased substantially, and that of N-acetyl-aspartate (NAA) decreased markedly after 24 hours. Increased Lac, Ace, and Ala might reflect anaerobic glycolysis associated with mitochondrial dysfunction, while decreased Glmi and NAA reveal brain tissue breakdown. The relationship between brain edema and tissue viability can be analyzed in detail using this simple traumatic model and MR techniques which will be useful in the development of therapeutic agents for brain injury.