Tracheal and Bronchial Developmental Abnormalities, and Inflammatory Diseases including Bronchiectasis, Cystic Fibrosis and Bronchiolitis.

Radiological inspection of the trachea is often limited to noting displacement by goitres or other large masses. Intraluminal masses are often not seen, and this is partly due to the poor demonstration of the trachea, carina and larger bronchi on low KV radiographs. Displacement and narrowing may occur both in the coronal and sagittal planes. The trachea forms the axis of the mediastinum. The normal trachea varies in diameter in men from about 1.3 to 2.5 cm, and in women from about 1 to 2.1 cm. Softening of the trachea may be caused by external pressure from long-standing external masses. Tracheal ring and bronchial cartilage calcification is relatively common over the age of 40 and is usually of no clinical importance, but may be more common with hypercalcaemia and hyperphosphataemia.