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Comparison of Metabolite Levels and Water Diffusion Between Cortical and Subcortical Strokes as Monitored by MRI and MRS

LABELLE, MARTIN MSc*; KHIAT, ABDESSLEM PhD*; Durocher, ANDRÉ MD; Boulanger, YVAN PhD*

Original Investigations
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Labelle M, Khiat A, Durocher A, et al. Comparison of metabolite levels and water diffusion between cortical and subcortical strokes as monitored by MRI and MRS. Invest Radiol 2001;36:155-163.

rationale and objectives.  Proton magnetic resonance spectroscopy (MRS) and functional imaging techniques are increasingly recognized as useful tools for the characterization of strokes. The aim of this study was to compare cortical and subcortical (lacunar) strokes by MRS and diffusion-weighted imaging (DWI) experiments as a function of time.

methods. Single-voxel MRS, DWI, and perfusion-weighted imaging data were recorded on patients with cortical (n = 7) or subcortical (n = 7) strokes in the acute, subacute, and chronic periods. Magnetic resonance spectra were acquired 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 lactate were observed at all times in the hyperintense DWI area of all lesions. Small decreases were measured in the subacute and chronic phases for the adjacent area of cortical strokes but not for the adjacent area of subcortical strokes. The existence of a surrounding affected area in subcortical strokes is deduced from a combination of MRS and DWI results, possibly corresponding 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 e-istence of affected tissue outside the hyperintense DWI regions in subcortical strokes. Cortical and subcortical strokes display different DWI and MRS characteristics.

From the Departments of *Radiology and †Neurology, Hôpital Saint-Luc du CHUM, Université de Montréal, Montréal, Québec, Canada.

Supported by the Fonds de la recherche en santé du Québec (FRSQ) and a grant from General Electric Medical Systems. Martin Labelle was the recipient of a PhD scholarship from the Fonds pour la formation de chercheurs et l’aide à la recherche (FCAR).

Reprint requests: Dr. Yvan Boulanger, Département de radiologie, Hôpital Saint-Luc du CHUM, 1058 St.-Denis, Montréal, Québec, Canada H2X 3J4; e-mail: yvan.boulanger@umontreal.ca

Received August 10, 2000, and accepted for publication, after revision, November 6, 2000.

© 2001 Lippincott Williams & Wilkins, Inc.