Cerebral proton and phosphorus-31 magnetic resonance spectroscopy in patients with subclinical hepatic encephalopathy

Background/Aims: In vivo magnetic resonance spectroscopy can be used to study cerebral metabolism non-invasively. We aimed to correlate H-1 and P-31 magnetic resonance spectral abnormalities in the brains of patients with subclinical hepatic encephalopathy. Methods: Eighteen patients were studied at 1.5T, with combined H-1 and P-31 magnetic resonance spectra obtained from multiple voxels in the cerebral cortex and basal ganglia. Peak area ratios of choline, glutamine/glutamate, relative to creatine in the H-1 spectra and percentage phosphomonoesters, phosphodiesters and beta NTP signals relative to total P-31 signals in the P-31 spectra were measured. Results: Six patients did not complete the full examination - P-31 results are available from 12 patients only. Relative to creatine, there were reductions in choline and elevations in glutamine/glutamate, varying across the brain with choline significantly reduced in occipital cortex (p<0.05) and glutamine/glutamate most significantly elevated in temporo-parietal cortex (p<0.0001). Percentage phosphomonoester (p<0.05), phosphodiester (p<0.05) and beta NTP (p<0.005) signals were significantly decreased in basal ganglia spectra. No correlation was found between the magnitude of H-1 and P-31 MRS changes, except between percentage phosphodiester decrease and glutamine/glutamate to creatine increase in occipital cortex. Conclusion: The results of this study point to a multifactorial aetiology for this condition.