Early temporal variation of cerebral metabolites after human stroke. A proton magnetic resonance spectroscopy study

Symbiosis between in vivo and in vitro NMR spectroscopy: the creatine, N-acetylaspartate, glutamate, and GABA content of the epileptic human brain

High resolution 1H NMR spectroscopy was used to analyze temporal lobe biopsies obtained from patients with epilepsy. Heat-stabilized cerebrum, dialyzed cytosolic macromolecules, and perchloric acid extracts were studied using one- and two-dimensional spectroscopy. Anterior temporal lobe neocortex was enriched in GABA, glutamate, alanine, N-acetylaspartate, and creatine. Subjacent white matter was enriched in aspartate, glutamine, and inositol. The N-acetylaspartate/creatine mole ratio was lower in anterior temporal neocortex with mesial (0.66) than neocortical (0.80) temporal lobe epilepsy. Human brain biopsy samples were separated into crude and refined synaptosomes, neuronal cell bodies, and glia using density gradient centrifugation. Neuronal fractions were enriched in glutamate and N-acetylaspartate. Glial cell fractions were enriched in lactate, glutamine, and inositol. The creatine content was the same in biopsied epileptic cortex (8.8-8.9 mmol/kg) and normal in vivo occipital lobe (8.9 mmol/kg). Glutamate content was higher in epileptic cortex at biopsy (10.1-10.5 mmol/kg) than normal in vivo occipital lobe (8.8 mmol/kg). GABA content was higher in biopsies of epileptic cortex (2.3-2.2 mmol/kg) than in normal in vivo occipital lobe (1.2 mmol/kg). N-acetylaspartate content was lower in biopsied epileptic temporal cortex (5.8-6.8 mmol/kg) than normal in vivo occipital lobe (8.9 mmol/kg). Paired in vivo and ex vivo measurements are critical for a firm understanding of the changes seen in the 1H-spectra from patients with epilepsy.

Proton spectroscopy of human stroke: assessment of transverse relaxation times and partial volume effects in single volume steam MRS

Proton T2 relaxation times were measured in 13 stroke patients and 13 aged-matched normal subjects at 2.1 T. Spectra were acquired from an 8-cc volume using the STEAM sequence with echo times (TE) of 30.4 ms and 270.0 ms and repetition time of 2.8 s. Transverse relaxation times were estimated using two-point calculations. Percentage volume of infarct in the STEAM voxel was measured on spin-echo MRI encompassing the infarct and correlated with the peak amplitude of N-acetylated compounds (NA). T2 values of NA, creatine, and choline resonances showed no significant difference between patients and controls. T2 for lactate in patients was 780 +/- 257 ms, respectively (mean +/- SE, n = 7). In stroke patients, high inverse correlation was found between the absolute NA signal and partial volume of normal brain contributing to each spectrum (p < .001, r = 0.97). Together with unchanged T2, this suggests that NAA largely disappears from infarcted tissue within 24 hr postinfarct.