Assessing skeletal muscle mass based on the cross-sectional area of muscles at the 12th thoracic vertebra level on computed tomography in patients with oral squamous cell carcinoma.

Abstract

This study aimed to create a formula to estimate the third lumbar vertebra (L3)1 level skeletal muscle cross-sectional area (CSA), known as a standard value to evaluate skeletal muscle mass on computed tomography (CT), using the twelfth thoracic vertebra (Th12) level skeletal muscle CSA on chest CT. This retrospective observational study included patients aged 40+years with a diagnosis of oral squamous cell carcinoma (n=164). Skeletal muscle CSA on CT images was measured using the Th12 and the L3 levels of pretreatment CT scans. The predictive formula was created based on the five-fold cross-validation method with a linear regression model. Correlations between the predicted L3-level CSA and the actual L3-level CSA were evaluated using r and Intraclass Correlation Coefficients (ICC). The predictive formula for L3-level CSA from Th12-level CSA was: CSA at L3 (cm2)=14.143+0.779 * CSA at Th12 (cm2) - 0.212 * Age (y)+0.502 * Weight (kg)+13.763 * Sex. Correlations between the predicted and measured L3-level CSA were r=0.915 [0.886-0.937] and ICC=0.911 [0.881-0.934]. We developed a formula for predicting skeletal muscle mass from the Th12-level CT slice. The predicted L3-level CSA correlated with the measured L3-level CSA.