Transverse thoracic diameter in frontal chest radiographs of an adult Nigerian population

Normal standards for thoracic dimensions that are available in our environment are often based on studies conducted on Caucasians. Application of such published data to a Nigerian population may lead to erroneous conclusions in terms of clinical implication. Our study aimed to establish age and sex specific transverse thoracic diameter (TD) for our environment. The TD of 303 males and females aged between 20 and 93 were obtained in a cross sectional study at a tertiary hospital. The mean values for the 20-39, 40-59 and the 3 60-year-old males were 29.6, 29.0, 27.8 cm respectively. The corresponding values for females were 26.3, 27.1 and 25.1 cm. Males had significantly larger thoracic diameter than females. The largest mean TD in males and females were in the 20-39 and 40-59 age groups respectively. The TD had a significant positive correlation with weight, height, body mass index and body surface area. The best correlations were with body surface area and weight. Nigerians have a smaller TD than Caucasians. Smaller TD in Nigerians is likely to be responsible for their high cardiothoracic ratios in comparison with Caucasians or Asians.