Age and Sex-Specific Normative Cardiothoracic Ratio Values in Nigerian Children Aged 9–13 Years: A Cross-Sectional Radiographic Study

Abstract

Aim
The cardiothoracic ratio (CTR) is one of the most widely used radiographic indices for evaluating cardiac size in paediatric populations, particularly in regions where advanced cardiac imaging is limited or unavailable. Despite its longstanding clinical application, normative CTR values for Nigerian children, especially in the South-South region, are inadequate. This study aimed to establish age- and sex-specific normative CTR values in healthy children aged 9–13 years in Port Harcourt, Nigeria, using standardised posteroanterior (PA) chest radiographs.
Method
Radiographic evaluation of the cardiac diameter was performed in 362 children (222 males, 140 females). Cardiac and thoracic diameters were obtained from posterior-anterior (PA) chest radiographs, and CTR was calculated as a percentage of cardiac to thoracic width. Data were analysed using descriptive statistics, t-tests, ANOVA, and Pearson correlations, with significance set at p < 0.05.
Result
The overall mean CTR was 45.4%. CTR increased progressively with age for both sexes: in males from 43.6% at age nine to 46.7% at ages twelve and thirteen, and in females from 43.3% at age nine to 47.4% at age twelve. Although males exhibited larger thoracic diameters, CTR values did not differ significantly between sexes (p = 0.12). Cardiac and thoracic diameters increased significantly with age (p < 0.001). A weak but significant correlation was observed between age and CTR (r = 0.18, p = 0.03).
Conclusion
The study provides age- and sex-specific CTR reference values for Nigerian school-aged children and offers clinically relevant data for interpreting paediatric chest radiographs. These findings support the use of population-specific CTR norms for diagnosing cardiomegaly and related conditions in regions with similar demographic characteristics.