BACKGROUND: Skeletal muscle alterations are associated with higher mortality and morbidity in patients with liver cirrhosis. Assessing these changes seems to be a promising method for identifying patients at a high risk of poor outcomes following liver transplantation (LT). This is particularly important given the current global shortage of organ donors. However, evidence of the impact of these alterations on the prognosis of patients undergoing LT is inconclusive. The aim of our prospective study was to evaluate the impact of skeletal muscle changes, reflected in sarcopenia, myosteatosis and metabolic changes in the calf muscles, on perioperative outcomes and long-term survival after LT. We also sought to determine the posttransplant evolution of the resting muscle metabolism. METHODS: We examined 134 adult LT candidates. Of these, 105 underwent LT. Sarcopenia and myosteatosis were diagnosed by measuring the skeletal muscle index and mean psoas muscle radiation attenuation, respectively, which were obtained from computed tomography (CT) scans taken during pretransplant assessment. Additionally, patients underwent 31P MR spectroscopy (MRS) of the calf muscles at rest before LT and 6, 12 and 24 months thereafter. The median follow-up was 6 years. RESULTS: Patients with abnormal 31P MRS results and CT-diagnosed myosteatosis prior to LT had significantly worse long-term survival after LT (hazard ratio (HR), 3.36; 95% confidence interval (CI), 1.48-7.60; p = 0.0021 and HR, 2.58; 95% CI, 1.06-6.29; p = 0.03, respectively). Multivariable analysis showed that abnormal 31P MR spectra (HR, 3.40; 95% CI, 1.50-7.71; p = 0.003) were a better predictor of worse long-term survival after LT than myosteatosis (HR, 2.78; 95% CI, 1.14-6.78; p = 0.025). Patients with abnormal 31P MR spectra had higher blood loss during LT (p = 0.038), required a higher number of red blood cell transfusions (p = 0.006) and stayed longer in ICU (p = 0.041) and hospital (p = 0.007). Myosteatosis was associated with more revision surgeries following LT (p = 0.038) and a higher number of received red blood cell transfusion units (p = 0.002). Sarcopenia had no significant effect on posttransplant patient survival. An improvement in the resting metabolism of the calf muscles was observed at 12 and 24 months after LT. CONCLUSIONS: Abnormal 31P MRS results of calf muscles were superior to CT-based diagnosis of myosteatosis and sarcopenia in predicting perioperative complications and long-term survival after LT. Resting muscle metabolism normalized 1 year after LT in most recipients.

• Keywords
• 31P MR spectroscopy, liver transplantation, myosteatosis, sarcopenia, skeletal muscle,
• MeSH
• Adult MeSH
• Muscle, Skeletal * diagnostic imaging   metabolism   MeSH
• Middle Aged MeSH
• Humans MeSH
• Magnetic Resonance Spectroscopy * methods   MeSH
• Tomography, X-Ray Computed * methods   MeSH
• Prognosis MeSH
• Prospective Studies MeSH
• Sarcopenia etiology   metabolism   MeSH
• Aged MeSH
• Liver Transplantation * MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH

Most in vivo 31P MR studies are realized on 3T MR systems that provide sufficient signal intensity for prominent phosphorus metabolites. The identification of these metabolites in the in vivo spectra is performed by comparing their chemical shifts with the chemical shifts measured in vitro on high-field NMR spectrometers. To approach in vivo conditions at 3T, a set of phantoms with defined metabolite solutions were measured in a 3T whole-body MR system at 7.0 and 7.5 pH, at 37 °C. A free induction decay (FID) sequence with and without 1H decoupling was used. Chemical shifts were obtained of phosphoenolpyruvate (PEP), phosphatidylcholine (PtdC), phosphocholine (PC), phosphoethanolamine (PE), glycerophosphocholine (GPC), glycerophosphoetanolamine (GPE), uridine diphosphoglucose (UDPG), glucose-6-phosphate (G6P), glucose-1-phosphate (G1P), 2,3-diphosphoglycerate (2,3-DPG), nicotinamide adenine dinucleotide (NADH and NAD+), phosphocreatine (PCr), adenosine triphosphate (ATP), adenosine diphosphate (ADP), and inorganic phosphate (Pi). The measured chemical shifts were used to construct a basis set of 31P MR spectra for the evaluation of 31P in vivo spectra of muscle and the liver using LCModel software (linear combination model). Prior knowledge was successfully employed in the analysis of previously acquired in vivo data.

• Keywords
• 31P MRS, LCModel, in vivo MR spectroscopy, liver, muscle,
• MeSH
• Adenosine Diphosphate metabolism   MeSH
• Adenosine Triphosphate metabolism   MeSH
• Phosphatidylcholines metabolism   MeSH
• Phosphatidylethanolamines metabolism   MeSH
• Phosphates metabolism   MeSH
• Phosphorus metabolism   MeSH
• Liver metabolism   MeSH
• Muscle, Skeletal metabolism   MeSH
• Humans MeSH
• Nuclear Magnetic Resonance, Biomolecular * MeSH
• Pilot Projects MeSH
• Software * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Evaluation Study MeSH
• Names of Substances
• Adenosine Diphosphate MeSH
• Adenosine Triphosphate MeSH
• Phosphatidylcholines MeSH
• Phosphatidylethanolamines MeSH
• Phosphates MeSH
• Phosphorus MeSH