Variations of QCT-based abdominal and paravertebral muscle tissue content by age and gender

The interaction between muscles and fat tissue has a significant impact on human health. The speed of muscle atrophy and fat infiltration varies in different genders and age groups. The study aims to observe the changes of fat and muscle parameters of abdominal tissue and paravertebral muscle with age and gender, and further to explore the characteristics of muscle atrophy and fat infiltration with age and gender through changes in the proportion of paravertebral muscle content to abdominal tissue content.

713 subjects who came to our hospital for physical examination of chest low-dose Computed Tomography (LDCT) scanning from September 1, 2021 to September 1, 2022 were collected. The scanning sequence and post-processing of quantitative Computed Tomography (QCT) were performed on them. The contents (including mass and area) of abdominal overall fat, visceral fat, visceral soft tissue, paravertebral intramuscular fat and paravertebral intramuscular muscle at the central level of L2 vertebrae were obtained. Then calculate the proportion of paravertebral intramuscular fat content to overall fat content, paravertebral intramuscular fat content to visceral fat content, and paravertebral intramuscular muscle content to visceral soft tissue content. Group the subjects by age and gender and observe the characteristics of changes in each parameter with age and gender.

There was a significant positive correlation (r = 0.637-0.999, P<0.001) between the mass and area in the overall fat, visceral fat, visceral soft tissue, as well as paravertebral intramuscular fat and muscle. The content of visceral fat (for mass: F = 3.645, P = 0.006; for area: F = 3.406, P = 0.009) and paravertebral intramuscular fat (for mass: F = 3.455, P = 0.009; for area: F = 3.750, P = 0.005) in males increased with age, while the muscle content of paravertebral muscle (for mass: F = 4.556, P = 0.001; for area: F = 4.077, P = 0.003) decreased. The percentage of paravertebral intramuscular fat content to overall fat content (for mass: F = 3.522, P = 0.008; for area: F = 3.454, P = 0.009), paravertebral intramuscular fat content to visceral fat content (for mass: F = 2.485, P = 0.043; for area: F = 2.503, P = 0.042) in males increased with age, and the percentage of paravertebral intramuscular muscles content to visceral soft tissue content (for mass: F = 3.408, P = 0.009; for area: F = 2.956, P = 0.020) decreased with age. For females, the content of overall fat (for mass: F = 12.476, P<0.001; for area: F = 12.301, P<0.001), visceral fat (for mass: F = 17.878, P<0.001; for area: F = 17.861, P<0.001) and paravertebral intramuscular fat (for mass: F = 6.399, P<0.001; for area: F = 6.960, P<0.001) increased with age, the percentage of paravertebral intramuscular fat content to overall fat content (for mass: F = 4.342, P = 0.002; for area: F = 4.068, P = 0.003), paravertebral intramuscular fat content to visceral fat content (for mass: F = 2.986, P = 0.019; for area: F = 2.801, P = 0.026) decreased before 60y and increased after 61y.

The fat and muscle content of abdominal tissues and paravertebral muscles have different characteristics in different age groups. Age and gender factors should be paid attention to when solving the problems of fat and muscle changes in clinic.