Subcutaneous Fat Thickness of the Lower Limb is Associated with Trunk Muscle Mass in Patients with Hepatocellular Carcinoma: A Simple Assessment for Sarcopenia Using Conventional Ultrasonography

Abstract

Objective: Trunk muscle mass can be evaluated by skeletal muscle index (SMI), which is a prognostic factor in patients with hepatocellular carcinoma (HCC); however, this requires the use of computed tomogra-phy, and a simpler assessment for trunk muscle mass is urgently needed. We aimed to examine whether an association between SMI and lower extremity compartments including muscle and subcutaneous fat thickness of lower limbs (SFT-LL) could be identified by means of ultrasonography in patients with HCC. Methods: We retrospectively enrolled male patients with HCC (n=30). Trunk muscle mass was evaluated by SMI using computed tomography. Ultrasonography was used for assessment of muscle and SFT-LL. Factors associated with SMI were evaluated by decision-tree analysis. Results: There was no significant correlation between SMI and muscle thickness of lower limbs. However, a significant correlation was seen between SMI and left SFT-LL (r=0.406, P=0.026). In decision-tree analysis for SMI, left SFT-LL was selected as the initial split variable with an optimal cut-off value of 5 mm. In patients with left SFT-LL ≥ 5 mm, SMI was 39.4±3.4 cm2/m2, whereas SMI was 31.6±6.3 cm2/m2 in patients with left SFT-LL <5 mm. Conclusion: Left SFT-LL evaluated by ultrasonography was associated with SMI. Thus, ultrasonography may be a useful tool to evaluate trunk muscle mass. Moreover, left SFT-LL may be a useful indicator of sarcopenia in patients with HCC.