CT evaluation of normal thoracic cage and its development in Chinese children

Background: To establish objective data for evaluation of normal chest and its development in Chinese children. Materials and methods: A computed tomography of the lower chest was performed in 75 normal chinese children. The pectus index (a/c), depression (b/c), asymmetry (b'/b), and flatness (a/b) of the chest wall were evaluated, where a was the maximum transverse diameter of the chest, b and b' were the maximum sagittal diameter of the left and right chest respectively, and c was the shortest midline sagittal diameter of the lower chest. Results: The pectus index significantly increased from 2.34 ± 0.26 in group A (n = 22, 3 to 6-year-old) to 2.58 ± 0.24 in group B (n = 30, 7 to 11-year-old) (p = 0.002), and to 2.63 ± 0.33 in group C (n = 23,12 to 16-year-old) (p = 0.002). The degree of asymmetry was significantly different between groups B and C (1.02 ± 0.04 versus 0.99 ± 0.04, p = 0.024). The degree of depression was significantly different between groups A and B (1.49 ± 0.11 versus 1.58 ± 0.10, p = 0.0009) and groups A and C (1.49 ± 0.11 versus 1.60 ± 0.09, p = 0.0009). The degree of flatness was 1.57 ± 0.11 in group A; 1.64 ± 0.10 in group B; and 1.64 ± 0.14 in group C. Conclusion: The above findings suggest that the thoracic cage grows more in the transverse direction as a child grows. This normal data can be used for assessing severity of chest wall deformity and its surgical outcome.