Metabolic and neurological patterns in chronic cerebral infarction: a single-voxel 1H-MR spectroscopy study.

The details of brain metabolism in chronic cerebral infarcts have not been clarified. Using proton MR spectroscopy (1H-MRS) at 1.5 T, we measured biochemical changes in 16 patients with large infarcts involving the motor cortex in the chronic phase (median 293.9 days) and related the findings to clinical data. Localised spectra were obtained using point-resolved spectroscopy, with an echo time of 270 ms. Regions of interest were placed on the frontal lobe, including the precentral gyrus and central sulcus. Motor function was assessed by the manual muscle power test at the time of the 1H-MRS study. Only three patients with severe paresis had no signal in the lesions and a lactate signal was obtained in 13 cases. N-acetyl aspartate (NAA) was observed in 4 cases with recanalisation of an occluded vessel. Motor function correlated strongly with the NAA/choline-containing compounds (Cho) ratio (P < 0.01) and lactate/Cho ratio (P < 0.01). We found various metabolic patterns, reflecting residual neurological function.

Differentiation of cerebral radiation necrosis from tumor recurrence by proton magnetic resonance spectroscopy.

Proton magnetic resonance spectroscopy (1H MRS) was evaluated for distinguishing between radiation necrosis and recurrent glioma in 11 patients after high-dose radiotherapy. Six patients had a histological diagnosis of recurrent glioma. Four patients had a histological diagnosis of radiation necrosis and one had a clinical course consistent with the diagnosis of radiation necrosis. 1H MRS showed cases of radiation necrosis had two characteristic 1H MRS patterns: markedly increased lactate/creatine and phosphocreatine (Cr) ratio and decreased choline-containing compounds/Cr ratio compared to that of recurrent glioma; or all the major metabolites were completely diminished. The N-acetyl aspartate signal was not helpful for differential diagnosis. 1H MRS is a potentially useful method for differentiating tumor recurrence from radiation necrosis in patients treated for malignant glioma.

Transient ipsilateral blood flow reduction in the thalamus and cerebral cortex after pontine infarction.

Remote cerebral hypoperfusion associated with pontine lesions is rare. We describe a patient who showed transient ipsilateral hypoperfusion in the thalamus and cerebral cortex after a pontine infarct. This resolved within 8 days after onset. Anatomical considerations strongly suggested involvement of the cerebellothalamocortical pathway in this case.

Cortical spectroscopy: localized spectroscopy of the cerebral cortex in rats.

A method for obtaining nuclear magnetic resonance (NMR) spectroscopic signals confined to the cerebral cortex in rat using a cortical coil constructed based on the principles of the zig-zag coil is described. We obtained 31P NMR spectra of normal cerebral cortex and cold-induced injured cortex using this cortical coil. The cortical coil clearly demonstrated an increase in inorganic phosphate (Pi) confirmed to cerebral cortex which, by contrast, the conventional planar surface coil failed to detect. There are significant metabolic differences between cortex and subcortical tissues. The technique described here, capable of assessing cortical metabolism in vivo without contamination by the underlying tissue, has substantial application to studies of cerebral metabolism.

Intrauterine fetal brain NMR spectroscopy: 1H and 31P studies in rats.

Fetal brain metabolism was investigated in utero noninvasively using multinuclear nuclear magnetic resonance spectroscopy in rats at two representative prenatal stages: early (17-18 days) and late (20-21 days) stages. Phosphorus-31 (31P) spectroscopy revealed that phosphocreatine is significantly lower in the early stage and increases to the level of early neonates by the late prenatal stage. Intracellular pH at the early stage was found to be strikingly high (7.52 +/- 0.21) and decreased to a level similar to that of neonates by the late stage (7.29 +/- 0.07). Phosphomonoester levels at both stages were similar to the values reported for early neonates. Water-suppressed proton (1H) spectroscopy demonstrated a distinctive in vivo fetal brain spectral pattern characterized by low levels of N-acetyl aspartate and high levels of taurine. High-resolution proton spectroscopy and homonuclear chemical-shift correlate spectroscopy of brain perchloric acid extracts confirmed these in vivo findings. In vitro 31P spectroscopy of acidified chloroform methanol extracts showed the characteristic membrane phospholipid profiles of fetal brain. The phosphatidylethanolamine (PE)-to-phosphatidylcholine (PC) ratio (PE/PC) did not show significant changes between the two stages at 0.40 +/- 0.11, a value similar to that of early neonates.