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

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 (Gln), glutamate (Glu), total creatine (tCr), choline‐containing compounds (Cho), and myo‐inositol (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. Magn Reson Med 45:383–389, 2001. © 2001 Wiley‐Liss, Inc.