Association between quantitative CT-derived body composition and lung low-attenuation area percentage: discrimination of high LAA% burden

Objective To investigate the associations between quantitative CT (QCT)-derived body composition parameters and CT-derived low-attenuation area percentage (LAA%), and to evaluate their ability to discriminate participants with high LAA% burden. Methods A total of 260 individuals aged ≥40 years who underwent chest CT and QCT during health examinations at Kaifeng Central Hospital from January 2023 to January 2025 were retrospectively included. The study cohort was not defined as a clinically diagnosed COPD population, and a clinical diagnosis of COPD was not required for inclusion. Clinical and body composition data were collected, and the participants were categorized into grades 0, 1, 2, and 3 according to CT-derived LAA−950%. The general data and body composition of each group were compared. Spearman correlation analysis was used to assess unadjusted associations between QCT-derived body composition parameters and LAA%. Covariate-adjusted associations were further evaluated using Gamma generalized linear models adjusted for age, sex, and BMI. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the discriminative performance of QCT-derived body composition parameters for LAA% grade 3. Results Participants in LAA% grade 3 had the lowest pectoralis major muscle area (PMcsa), pectoralis major muscle index (PMI), pectoralis major muscle density (PMD), subcutaneous fat content, total muscle area of the same layer, and L1−2 vertebral volumetric bone mineral density (vBMD), while the total fat infiltration rate of the pectoralis major muscle was the highest ( P < 0.05). LAA% was negatively correlated with PMcsa, PMD, PMI, subcutaneous fat content, total muscle area of the same layer, and vBMD, and positively correlated with total fat infiltration rate of pectoralis major muscle ( P < 0.05). The apparent AUCs of the body composition parameters for discriminating LAA% grade 3 ranged from 0.733 to 0.887, while the bootstrap-corrected AUCs ranged from 0.726 to 0.881, indicating generally stable moderate-to-good discriminative performance. Conclusions QCT-derived body composition parameters are associated with CT-derived LAA%, and several of these parameters show good discriminative performance for identifying participants with LAA% grade 3. These findings support the potential value of integrated CT-based assessment of lung attenuation and body composition.