Localized 1H NMR spectroscopy in patients with chronic hepatic encephalopathy. Analysis of changes in cerebral glutamine, choline and inositols.

Localized, short echo 1H magnetic resonance spectra from an area in the parietal cortex of three patients suffering from chronic hepatic encephalopathy are compared with equivalent spectra obtained from healthy control subjects. Three significant differences are found: elevated glutamine, decreased inositol, and decreased choline peak intensities. The elevation of cerebral glutamine concentration is expected as a consequence of the presumed chronic hyperammonemia in this disease. The finding of a 50% change in the inositol peak is physiologically unexpected and so far unaccounted for. Data acquisition and processing parameters are described in detail. To further define spectral abnormalities, which were readily detected in untransformed spectra, a simple data analysis scheme has been used that consists of post-acquisition low-frequency filtering, a lineshape transformation, and a difference technique to clarify spectral changes.