Deep sulcus sign

Deep Sulcus Sign
51 year old male with recent trauma with multiple rib fractures on the left resulting in flail chest. Rib fixation hardware is present on the left. Fractures are also presnt on the right and there are bilaterl chest tubes.
A subpulmonic pneumothoraxis present
Ashley Davidoff TheCommonVein.net 136507
Deep Sulcus Sign
51 year old male with recent trauma with multiple rib fractures on the left resulting in flail chest. Rib fixation hardware is present on the left. Fractures are also present on the right and there are bilateral chest tubes.
A subpulmonic pneumothorax is present with the displaced pleura noted (b, white arrowheads) and the basal pneumothorax (b blue arrowhead). Note the patient is in the semi-upright position and likely more supine than upright based on the position of the pneumothorax
Ashley Davidoff TheCommonVein.net 136507cL
Deep sulcus sign. Anteroposterior supine radiograph of the chest in a patient with bilateral pneumothoraces. The costophrenic angles are lucent and extend inferiorly, signifying pleural air that has risen to the dependent portion of the thorax in these regions.
Source
Signs in Thoracic Imaging
Journal of Thoracic Imaging 21(1):76-90, March 2006.

The presence of radiolucency in a deep costophrenic sulcus on a supine thoracic radiograph (Fig. 8) is characteristic of a pneumothorax in a supine patient.31 Intrapleural air rises to the highest portion of the hemithorax leading to the presence of a lucency in the anteromedial, subpulmonic, and lateral basilar space adjacent to the diaphragm.3,4,31 It is useful in confirming suspected pneumothorax on AP supine radiography in compromised patients, such as those in the intensive care setting.4