Time course of NAA T2 and ADC(w) in ischaemic stroke patients: 1H MRS imaging and diffusion-weighted MRI.
OBJECTIVE
Proton spectroscopy and quantitative diffusion-weighted imaging (DWI) were used to investigate the pertinence of N-acetyl aspartate (NAA) as a reliable marker of neuronal density in human stroke.


METHODS
The time courses of tissue water apparent diffusion coefficient (ADC(w)) and metabolite T2 were investigated on a plane corresponding to the largest area of cerebral infarction, within and outside the site of infarction in 71 patients with a large cortical middle cerebral artery territory infarction.


RESULTS
Significant reductions are seen in NAA T2 deep within the infarction during the period comprised between 5 and 20 days postinfarction; the relaxation times appearing to normalise several months after stroke. After an acute reduction in ADC(w), the pseudonormalisation of ADC(w) occurs at 8-12 days after the ischaemic insult. The minimum in N-acetyl aspartate T2 relaxation times and the pseudonormalisation of ADC(w) appear to coincide.


CONCLUSIONS
The data suggest that modifications in the behaviour of the observed proton metabolites occur during the period when the vasogenic oedema is formed and cell membrane integrity is lost. For this reason, NAA may not be a reliable marker of neuronal density during this period.
Walker
Paul M
PM
Department of Magnetic Resonance Spectroscopy, Hôpital d'Enfants, University Hospital of Dijon, 2 Boulevard du Lattre de Tassigny, 21033 Dijon, France. pwalker@u-bourgogne.fr
Ben Salem
Douraïed
D
Lalande
Alain
A
Giroud
Maurice
M
Brunotte
François
F
D000368:Aged; D000704:Analysis of Variance; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism*; D002545:Brain Ischemia / Q000378:metabolism*; D001931:Brain Mapping; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D020521:Stroke / Q000378:metabolism*; D014316:Tritium
D014316:Tritium; D001224:Aspartic Acid; C000179:N-acetylaspartate