Computed tomography-derived assessments of regional muscle volume: Validating their use as predictors of whole body muscle volume in cancer patients

Objective:Evaluate the accuracy of CT-derived regional skeletal muscle volume (SMV) measurements to predict whole body SMV in patients with melanoma.Methods:148 patients with advanced melanoma who underwent whole body positron emission tomography/CT were studied. Whole body SMV was measured on CT and used as the reference standard. CT-derived regional measures of SMV were obtained in the thorax, abdomen, pelvis, and lower limbs. Models were developed on a discovery cohort (n-98), using linear regression to model whole body SMV as a function of each regional measure, and clinical factors. Predictive performance of the derived models was evaluated in a validation cohort (n = 50) by estimating the explained variation (R2) of each model.Results:In the discovery cohort, all regional SMV measurements were significantly associated with whole body SMV [β1 range: 0.673–1.153, all p < 0.001)]. The magnitude of association was greatest for pelvic regional measurements {β = 1.153, [95% confidence interval (0.989, 1.3...