title: In vivo proton magnetic resonance spectroscopy for the evaluation of hepatic encephalopathy in dogs.
abstract: OBJECTIVE
  To investigate clinical use of proton magnetic resonance spectroscopy ((1)H MRS) and to compare metabolic brain bioprofiles of dogs with and without hepatic encephalopathy.
  
  
  METHODS
  6 dogs with hepatic encephalopathy and 12 control dogs.
  
  
  METHODS
  Conventional MRI and single-voxel (1)H MRS were performed with a 3-T magnet. Images for routine MRI planes and sequences were obtained. Single-voxel (1)H MRS was performed with a point-resolved sequence with a short echo time (35 milliseconds) and voxel of interest placement at the level of the basal ganglia. Metabolites of interest included the glutamine-glutamate complex (sum quantification of glutamate and glutamine), myoinositol, N-acetyl aspartate, total choline, and creatine. Data were analyzed with postprocessing fitting algorithm software, and metabolite concentration relative to water and ratios with creatine as the reference metabolite were calculated.
  
  
  RESULTS
  Compared with control dogs, dogs with hepatic encephalopathy had specific changes, which included significantly higher concentration relative to water of the glutamine-glutamate complex and significantly lower concentration of myoinositol. Choline and N-acetyl aspartate concentrations were also slightly lower in dogs with hepatic encephalopathy than in control dogs. No differences in creatine concentration were detected between groups.
  
  
  CONCLUSIONS
  (1)H MRS aided in the diagnosis of hepatic encephalopathy in dogs, and findings supported the assumption that ammonia is a neurotoxin that manifests via glutamine-glutamate complex derangements. Use of (1)H MRS may provide clinically relevant information in patients with subclinical hepatic encephalopathy, equivocal results of bile acids tests, and equivocal ammonia concentrations or may be helpful in monitoring efficacy of medical management.
authors.affiliation: Division of Diagnostic Imaging, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland.
authors.forename: Inés
authors.initials: I
authors.lastname: Carrera
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Kircher
authors.forename: Dieter
authors.initials: D
authors.lastname: Meier
authors.forename: Henning
authors.initials: H
authors.lastname: Richter
authors.forename: Katrin
authors.initials: K
authors.lastname: Beckman
authors.forename: Matthias
authors.initials: M
authors.lastname: Dennler
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology*; D016022:Case-Control Studies; D004283:Dog Diseases / Q000175:diagnosis*; D004285:Dogs; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D006501:Hepatic Encephalopathy / Q000175:diagnosis / Q000662:veterinary*; D007294:Inositol / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male
chemical_list: D005973:Glutamine; D018698:Glutamic Acid; D007294:Inositol