Normal anatomy of chest radiography

Abstract

Conventional chest radiography allows us to identify a bunch of structures and organs, including chest wall elements (e.g.: bones and soft tissue), pleural cavities, airways, pulmonary hila and vasculature, mediastinum, heart, aorta, and right and left lungs. This article aims to review anatomy of the structures examined by chest radiography through a didactic text with illustrations and figures from exams of our institution. The first things we should attempt to evaluate is the exam technique, patients characteristics and anatomy variants.  It is important to identify the breasts shadows, gastric bullae and hepatic opacification below the diaphragm. Among bone structures, we mainly evaluate the clavicles, shoulder joints, ribs, chest spine and the sternum. The costophrenic angles are the main marker of pleural diseases. Our evaluation should contemplate the airways (particularly trachea and carina), the pulmonary hila (right and left) and pulmonary vasculature. It is important to know the structures that compose the normal cardiomediastinal silhouette, so we can recognize mediastinal lesions and cardiovascular disease. Anatomically, the right lung differs from the left one, and the correlation between frontal and lateral images are essential to the precise location of the anomalies. At last, we should have familiarity with some common anatomical variants in chest radiography, like cervical ribs, costal cartilage calcifications and the Azygos vein lobe.