Background
Skeletal muscle depletion, referred to as sarcopenia, predicts morbidity and mortality in digestive surgery. Recent evidence has shown that intramuscular fat accumulation was linked to the severity of non-alcoholic steatohepatitis. The present study investigated the impact of intramuscular fat accumulation as well as skeletal muscle mass on patients undergoing living donor liver transplantation (LDLT).

Material and Methods
This study comprised 200 adult patients undergoing LDLT at our institution between January 2008 and October 2013. The quality and quantity of skeletal muscle were evaluated by intramuscular adipose tissue content (IMAC) and psoas muscle mass index (PMI) at the umbilical level, respectively. The correlations of IMAC or PMI with other factors, the overall survival rate in patients classified according to IMAC or PMI, the risk factors for poor survival, and the sequential changes of IMAC or PMI after LDLT were analyzed.

Results
IMAC was significantly correlated with age and PMI in male, age and BCAA-to-tyrosine ratio in female. PMI was significantly correlated with NH3 in male and skeletal muscle mass in both of male and female. The overall survival rate in patients with high IMAC or low PMI was significantly lower than in patients with normal IMAC or PMI (p<0.001). Multivariate analysis showed high IMAC and low PMI were independent risk factors for death after LDLT. IMAC and PMI temporarily got worse until 3-6 months after LDLT, and thereafter gradually recovered.

Conclusion
High IMAC and low PMI were closely involved with posttransplant mortality. Long-term postoperative nutritional therapy and rehabilitation are crucial.