Detection of cerebral metabolites in a canine model of ischemic stroke using H magnetic resonance spectroscopy

Proton magnetic resonance spectroscopy (¹H MRS) provides in vivo biochemical information on tissue metabolites. The purpose of this study was to investigate the serial metabolic changes of ¹H MRS in the cerebrum of ischemic dogs. An ischemic stroke was induced in five health laboratory beagle dogs by permanent middle cerebral artery occlusion using a silicone plug. ¹H MRS was serially performed three times with a 1.5-T MR system: before, three days after and 10 days after the stroke. Immunohistochemical staining was performed to determine the expression of neuronal nuclei (NeuN) and glial fibrillary acidic protein (GFAP) at both the ipsilateral and contralateral cerebral cortex. Reduced levels of N-acetyl-asparate (p < 0.05), choline (Cho), creatine (Cr) and myo-inositol (mI), and a marked increase in the lactate (Lac) level (p < 0.01) were found at three days after the stroke. At 10 days after the stroke, the levels of Lac significantly increased (p < 0.01); however, the other metabolites were partially elevated. The changes of Cr, Cho and mI were not statistically significant (p > 0.05) when the before and after stroke values were compared. There was a significant loss of NeuN and GFAP immunoreactivity at the ischemic core. ¹H MRS may be to a useful diagnostic tool for the evaluation of ischemic stroke in dogs.