title: Evaluation of ammonia metabolism in the skeletal muscles of patients with cirrhosis using N-13 ammonia PET.
abstract: OBJECTIVE
  Skeletal muscle is said to compensate for the decreased ammonia metabolism in patients with cirrhosis. Branched-chain amino acids (BCAA) are being used as a treatment for hyperammonemia, and are believed to decrease blood ammonia by consumption of BCAA in skeletal muscles. We examined ammonia metabolism of the skeletal muscles in patients with liver cirrhosis after administration of BCAA using 13N-ammonia positron emission tomography (PET).
  
  
  METHODS
  The subjects were patients with compensated or decompensated liver cirrhosis. PET studies were performed before and 2 hours after injection of BCAA. Serial dynamic PET scans (2 min x 10 frames) were started simultaneously with 13N-ammonia injection. The standardized uptake value (SUV) of both thighs was calculated.
  
  
  RESULTS
  In the patient with compensated liver cirrhosis, there was little difference in the rate of increase in SUV before to after administration of BCAA. However, in the patient with decompensated liver cirrhosis, the rate of increase in SUV after administration was higher than that before administration of BCAA.
  
  
  CONCLUSIONS
  Ammonia metabolism in the muscle of patients with liver cirrhosis could be examined noninvasively under physiological conditions using 13N-ammonia PET. The muscles were found to metabolize ammonia partially, and the role of this contribution to metabolism of ammonia in patients with decompensated liver cirrhosis is particularly important.
authors.affiliation: Department of Hepatology, Graduate School of Medicine, Osaka City University, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Nishiguchi
authors.forename: Susumu
authors.initials: S
authors.lastname: Shiomi
authors.forename: Etsushi
authors.initials: E
authors.lastname: Kawamura
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Ishizu
authors.forename: Daiki
authors.initials: D
authors.lastname: Habu
authors.forename: Kenji
authors.initials: K
authors.lastname: Torii
authors.forename: Joji
authors.initials: J
authors.lastname: Kawabe
mesh_terms: D000368:Aged; D000597:Amino Acids, Branched-Chain / Q000627:therapeutic use; D000641:Ammonia / Q000493:pharmacokinetics*; D005260:Female; D005355:Fibrosis / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000378:metabolism*; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000378:metabolism*; D009590:Nitrogen Radioisotopes / Q000493:pharmacokinetics; D013848:Thigh / Q000000981:diagnostic imaging; D014055:Tomography, Emission-Computed / Q000379:methods
chemical_list: D000597:Amino Acids, Branched-Chain; D009590:Nitrogen Radioisotopes; D000641:Ammonia