Multi-Parameter Imaging-Derived Muscle Assessment System for Older Adults: A Promising Muscle Function Evaluation Tool.

OBJECTIVE: This research aims to evaluate the utility of ultrasound, quantitative computed tomography (QCT) and their integration for assessing muscle function and physical performance in older adults at risk of sarcopenia. METHODS: A total of 142 elderly inpatients were recruited in this cross-sectional study and completed physical performance tests. Participants were categorized into three parts: Part 1 (n = 125) underwent ultrasound to measure rectus femoris (RF) cross-sectional area (CSA), vastus lateralis pennation angle (PA) and gastrocnemius PA and fascicle length (Lf); Part 2 (n = 80) received clinically indicated QCT to quantify muscle fat fraction at T11, T12, L3 and L4; Part 3 (n = 63) completed both. Diagnostic parameters valuable for reduced muscle function from Parts 1 and 2 were integrated in Part 3 using binary logistic regression to construct the cross-modal model, with diagnostic performance assessed by area under the curve (AUC). RESULTS: Ultrasound-derived parameters (CSA of RF, PA of medial gastrocnemius and Lf of lateral gastrocnemius) and QCT-measured muscle fat fraction were significantly correlated with physical performance. Age, CSA of RF and fat fraction of psoas major muscle at L4 were identified as independent predictors of decreased gait speed and impaired physical performance. The cross-modal models integrating these parameters demonstrated improved diagnostic performance, with AUCs of 0.912 for decreased gait speed and 0.892 for impaired physical performance. CONCLUSION: The ultrasound and CT-derived muscle assessment system offers an objective imaging tool for evaluating muscle function and physical performance in older adults, and may serve as a valuable tool for sarcopenia auxiliary diagnosis.