Changes in apparent diffusion coefficients of metabolites in rat brain after middle cerebral artery occlusion measured by proton magnetic resonance spectroscopy

Abstract

Diffusion-weighted proton MR spectroscopy and imaging have been applied to a rat brain model of unilateral middle cerebral artery occlusion between 1 and 4 hr post occlusion. Similar apparent diffusion coefficients (ADC) of most metabolites were observed within each hemisphere. In the ischemic ipsilateral hemisphere, the ADCs were (0.083-0.116)·10-3 mm2/sec for lactate (Lac), alanine (Ala), γ-amino butyric acid (GABA), N-acetyl aspartate (NAA), glutamine (Gin), glutamate (Glu), total creatine (tCr), choline-containing compounds (Cho), and myoinositol (Ins), in the contralateral hemisphere (0.138-0.158)·10-3 mm2/sec for NAA, Glu, tCr, Cho, and Ins. Higher ADCs was determined for taurine (Tau) in the ipsilateral (0.144·10-3 mm2/sec) and contralateral (0.198·10-3 mm2/sec) hemisphere. In the ischemic hemisphere, a relative ADC decrease to 65-75% was observed for NAA, Glu, tCr, Cho, Ins and Tau, which was similar to the decrease of the water ADC (to 67%). The results suggest a common cause of the observed ADC changes and provide a broader experimental basis to evaluate theories of water and metabolite diffusion. © 2001 Wiley-Liss, Inc.