MR diffusion and perfusion parameters: relationship to metabolites in acute ischaemic stroke.

Background: MR diffusion and perfusion imaging are used to identify ischemic penumbra, but there are few comparisons with neuronal loss and ischaemia in vivo. We compared N-acetyl aspartate (NAA, found in intact neurons) and lactate (anaerobic metabolism) with diffusion/perfusion parameters. Methods: We prospectively recruited patients with acute ischemic stroke and performed MR diffusion tensor, perfusion (PWI) and proton chemical shift spectroscopic imaging (CSI). We superimposed a 0.5 cm voxel grid on the diffusion-weighted images (DWI) and classified voxels as 'definitely abnormal', 'possibly abnormal', or normal on DWI appearance, and 'mismatch' for voxels in DWI/PWI mismatch areas. We compared metabolite (NAA, lactate), perfusion and ADC values in each voxel type. Results: NAA differentiated 'definitely' from 'possibly abnormal', and 'possibly abnormal' from 'mismatch' (both comparisons p