Aortic–thoracic Ratio in Nigerian Children: Normative Values and Sex Differences Corrected/edited Version

Abstract

Background: The aortic–thoracic ratio (ATR) is a simple radiographic index that relates aortic size to thoracic cavity width and may assist in recognizing abnormal aortic enlargement in children. Normative ATR data for African paediatric populations are scarce. Objective: To establish age- and sex-specific normative values for ATR in Nigerian children aged 9–13 years and to examine its relationship with age and sex. Methods: This cross-sectional radiographic study included 362 apparently healthy Nigerian children (222 males, 140 females) aged 9–13 years in Port Harcourt, Nigeria. Posteroanterior (PA) chest radiographs were used to measure aortic diameter (AD) at the level of the aortic arch and thoracic diameter (TD) as the maximal internal transverse diameter of the thoracic cavity. ATR was calculated as (AD/TD) × 100. Descriptive statistics were generated for AD, TD, and ATR by age and sex. Sex differences within age groups were evaluated using independent-sample t-tests, with p < 0.05 considered statistically significant. Results: The overall mean ATR for the study population was 22.4%. In both sexes, mean AD and TD increased with age. Among males, mean ATR rose from 21.4% at 9 years to 22.8% at 12–13 years; among females, mean ATR ranged from 21.9% at 9 years to 22.8% at 12 years. There was no statistically significant sex difference in ATR across the 9–13-year age range. Thoracic diameter was larger in males than in females in the 12-year age group, with a statistically significant difference in TD (p < 0.001). Conclusion: This study provides age- and sex-specific reference values for the aortic–thoracic ratio in Nigerian children aged 9–13 years. ATR appears to increase slightly with age while showing no meaningful sex-related differences within this range. These normative data may serve as a useful radiographic reference for assessing aortic size in Nigerian children and similar populations.