Differences in muscle composition and functionality: Exploring CT anatomical points and SARC-F components

•Thigh skeletal muscle radiodensity (SMD) independently correlates with overall SARC-F score.•Patients with cancer experiencing difficulties reported by SARC-F questions may exhibit significantly lower SMD values across all anatomical points.•Morphological muscle quality (SMD) warrants evaluation and management in patients with cancer. Our study aimed to 1) investigate the differences of muscle parameters in relation to each SARC-F component/question; and 2) explore the relationship between SARC-F score with these muscle parameters using various landmarks derived from computed tomography (CT) scans of patients with cancer. This study is a cross-sectional analysis of a cohort comprised of consecutive patients with cancer, displaying CT scans. SARC-F questionnaire was utilized as a proxy for muscle functionality, with a score ≥4 indicating a poor status. Muscle assessment via CT measurements was performed using single cross-sectional images at the level of the third lumbar vertebrae (L3) in the abdominal region, the thigh region, and the total gluteal region at the level of the second sacral vertebrae. Skeletal muscle (SM) cross-sectional area, SM index (normalized to height2), and SM radiodensity (SMD) were evaluated for all anatomical landmarks. A total of 128 patients were included in this analysis (53.1% females, 61.7% older adults). Patients with SARC-F scores ≥4 demonstrated significantly lower values of SMD across all landmarks assessed. Those reporting difficulties related to strength (P = 0.039), requiring assistance in walking (P = 0.033), and climbing stairs (P = 0.012) exhibited significantly lower SMD values at the L3 landmark. At gluteus and thigh levels, only patients experiencing difficulty climbing stairs (P = 0.012) showed significantly lower values of SMD. Only SMD at gluteus level was independently associated with SARC-F score (βadjusted –0.09, 95% CI –0.16 to –0.02). Our findings suggest that individuals with poor muscle composition may experience a higher risk of sarcopenia/poor muscle functionality.