Imaging of Pneumothorax

How to Identify Pneumothorax? Can we identify pneumothorax when supine?

1. How to Identify Pneumothorax?

The main features of pneumothorax are –

  • Lucent area in the thorax( Yellow arrow), which is devoid of broncho vascular markings.
  • Presence of a visceral pleural line ( red arrow).

2. Can we identify pneumothorax when supine?

Sometimes the patient will be too ill to go to the Xray department, or cannot be transported ( for example in a High Dependency Unit or an ICU). In such cases, the patient will be lying supine in his bed. In such cases, we should be able to detect a supine pneumothorax. In such cases, the air will lie anterior to the lungs. So we may not be able to visualize the air in the peripheral aspect of the thorax. Instead, it will be anterior to the lung, so –

a) The ipsilateral thorax will be more lucent.

b) The ipsilateral thorax will be larger ( giving rise to Deep sulcus sign).

C) Both the diaphragms will be visible.  Remember, that normally, only the dome is visible and the rest of the diaphragm is obscured by liver shadow.  But when air is present, it outlines the diaphragm and gives rise to the Double diaphragm sign.

Note the curvature of the diaphragm. The posterior aspect of the diaphragm is curved downwards. So, in a Chest Xray, only the anterior portion of the diaphragm will be visible. Because, the posterior aspect of the diaphragm will be obscured from hepatic or splenic shadow, which will be lying just beneath the dome of the diaphragm. However, when there is air beneath the diaphragm, the diaphragm will be visible. This is because, the diaphragm will be outlined by air on both sides, both superiorly and inferiorly.

Note the deep sulcus in the right hemithorax ( blue arrow), and also increased lucency of the right compared to the left side. This is a case of pneumothorax in patient, when taken in the supine position.

Note the deep sulcus on the right side; increased lucency of the right hemidiaphragm, and also the appreciation of 2 parts of the right diaphragm. This is also a case of supine pneumothorax.

Courtesy of Learning radiology.com

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