New Sign of Pneumothorax: Sharp Edge of Aorta on Prone Image

Author(s): Alan E. Oestreich

In the prone radiograph, a left pneumothorax may outline part of the upper descending aorta with a sharp interface (similar to the sharp edge of the lateral cardiac margin seen in supine radiographs). The sign is illustrated in a 2 month-old male infant with considerable bilateral lung disease.