Analysis of Respiratory Muscles Density in Different Age Groups Using CT Scans

Currently, there is lack of quantitative methods to assess respiratory muscle density, both in healthy patients and in patients with sarcopenia. In this study, we assess respiratory muscle density in patients with no known diagnosis of sarcopenia using CT images. We extracted the distributions of muscle density, defined in Hounsfield units, in the pectoralis major, pectoralis minor, intercostal and serratus muscles in young, middle-aged, and elderly adults. Results showed consistent changes across respiratory muscles in terms of density distributions in the different age groups, specifically a decrease in mean value, median value, and kurtosis, and an increase in standard deviation with increasing age. The Jensen-Shannon divergence was higher between patients from different age groups and lower between patients with different body mass index (BMI) from the same age group, suggesting a marginal effect of BMI on density. This study paves the way to future research aimed at assessing sarcopenia in respiratory muscles, for example to support the clinical management of patients with chronic respiratory disease.