Deep Sulcus Sign in Pneumothorax - Xray

So that u wont miss a pneumothorax in supine film. Since the gravity does rather a different play to the air trapped inside when the patient is supine


Deep sulcus sign


■On frontal view, larger lateral costodiaphragmatic recess than on opposite side

■Diaphragm may be inverted on side with deep sulcus
 
 

Left pneumothorax-deep sulcus sign., Lucency at left costophrenic angle which projects well below the

costophrenic angle on the opposite side is the "Deep sulcus sign" indicating the

presence of a pneumothorax on a supine radiograph of the chest

(Bullet is seen overlying the heart)

Source: Wikipedia and http://www.learningradiology.com/archives04/COW%20122-PTX-Deep%20Sulcus/deepsulcuscorrect.htm