Measurement of psoas muscle thickness/height at the level of the umbilicus on a computed tomography (CT) scan image. Axial CT scan at the level of the umbilicus in a patient with hepatitis B virus-related cirrhosis and a model for end-stage liver disease (MELD) score of 10 with no ascites. Psoas muscle thickness corresponds to the diameter of transversal psoas muscle (left-right arrow) perpendicular to the axial diameter (dotted left-right arrow).