Comparison of metabolite levels and water diffusion between cortical and subcortical strokes as monitored by MRI and MRS

RATIONALE AND OBJECTIVES. Proton magnetic resonance spectroscopy (MRS) and functional imaging techniques are increasingly recognized as useful tools f or the characterization of strokes. The aim of this study was to compare co rtical and subcortical (lacunar) strokes by MRS and diffusion-weighted imag ing (DWI) experiments as a function of time. METHODS, Single-voxel MRS, DWI, and perfusion-weighted imaging data were re corded on patients with cortical (n = 7) or subcortical (n = 7) strokes in the acute, subacute, and chronic periods. Magnetic resonance spectra were a cquired in three regions: hyperintense DWI area, adjacent area with normal DWI intensity, and contralateral area, Neurological deficits were estimated by the National Institutes of Health Stroke Scale, RESULTS, Decreases in N-acetylaspartate, choline-containing compounds, and creatine/phosphocreatine signal intensity as well as the presence of lactat e were observed at all times in the hyperintense DWI area of all lesions, S mall decreases were measured in the subacute and chronic phases for the adj acent area of cortical strokes but not for the adjacent area of subcortical strokes. The existence of a surrounding affected area in subcortical strok es is deduced from a combination of MRS and DWI results, possibly correspon ding to the ischemic penumbra, Differences were found between the two types of lesion, especially an increased time variability of apparent diffusion coefficients in subcortical strokes. CONCLUSIONS, Magnetic resonance spectroscopy provides evidence for the exis tence of affected tissue outside the hyperintense DWI regions in subcortica l strokes, Cortical and subcortical strokes display different DWI and MRS c haracteristics.