Feasibility of assessment of skeletal muscle mass on a single cross-sectional image at the level of the fourth thoracic vertebra

BackgroundSkeletal muscle mass (SMM) determined on computed tomography (CT) is emerging as a novel imaging biomarker. Cross-sectional area (CSA) of SMM at the level third lumbar vertebra (L3) abdominal considered clinical reference standard for measuring SMM. In certain patient groups, such those with oncological or non-oncological lung disease like COVID-19, chest CT may be available while an not. The purpose this study was to investigate whether determining feasible alternative CT.Research questionWhat correlation between measurements L3 and fourth thoracic (Th4)?Study design methodsIn we retrospectively analyzed series whole-body CT-scans trauma patients (N = 47) head neck cancer 194). All muscles were delineated single axial slice L3. erector spinae, levator scapulae, rhomboideus minor major pectoralis Th4. CSA Th4 compared using linear regression, multivariate regression model established.ResultsMuscle strongly correlates (r 0.791, p < 0.05). A incorporating characteristics arm positioning, age, sex, weight achieved stronger 0.856, 0.05).InterpretationSkeletal measured This allows diagnosing low clinically CT-scans. become prognostic triage tool when faced mechanical ventilator shortage.