PMC6402214_01
Chest X-ray (a) and chest CT (b). On both pictures, subcutaneous emphysema is apparent at the right side of the neck (thick white arrow) as well as air tracking in the centre of the mediastinum indicative for mediastinal emphysema or pneumomediastinum (thin white arrow). Chest CT reveals a pneumopericardium (thin black arrow) and a small pneumothorax (thick black arrow). The pericardium can be seen between the pneumopericardium and pneumothorax (black triangle).
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fig1
A chest X-ray showed subtle evidence of pneumomediastinum and right-sided mild subcutaneous emphysema in the neck (Figure 1(a), thick arrow) with air tracking in the centre of the mediastinum (Figure 1(a), thin arrow). This confirmed the presence of subcutaneous emphysema with a pneumopericardium, a large pneumomediastinum, and a small pneumothorax (Figure 1(b), Figure 3).
Mach band effect versus pneumomediastinum. Zoom in on the right cardiomediastinal border showing the edge enhancement along the cardiac margin. White arrows depicting the right cardiac border and black arrows depicting the mediastinal border of the right lung.
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fig2
There is a small denser line along the right cardiomediastinal margin (Figure 2) that is often present in normal X-rays and is attributed to an optical illusion known as the Mach Band effect (a visual pattern due to edge enhancement manifesting as a region of lucency adjacent to convex surfaces).
Chest CT showing extensive subcutaneous and mediastinal emphysema compatible with a large pneumomediastinum (white arrow), a pneumopericardium (thin black arrow, with pericardium marked by the black triangle), and a small pneumothorax (thick black arrows).
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fig3
This confirmed the presence of subcutaneous emphysema with a pneumopericardium, a large pneumomediastinum, and a small pneumothorax (Figure 1(b), Figure 3).