On the PA chest-film it is important to examine all the areas where the lung borders the diaphragm, the heart and other mediastinal structures.
At these borders lung-soft tissue interfaces are seen resulting in a:
Line or stripe - for instance the right para tracheal stripe.
Silhouette - for instance the normal silhouette of the aortic knob or left ventricle
These lines and silhouettes are useful localizers of disease, because they can be displaced or obscured with loss of the normal silhouette. This is called the silhouette sign, which we will discuss later.
The paraspinal line may be displaced by a paravertebral abscess, hemorrhage due to a fracture or extravertebral extension of a neoplasm.
Widening of the paratracheal line (> 2-3mm) may be due to lymphadenopathy, pleural thickening, hemorrhage or fluid overload and heart failure.
Displacement of the para-aortic line can be due to elongation of the aorta, aneurysm, dissection and rupture.
The anterior and posterior junction lines are formed where the upper lobes join anteriorly and posteriorly. These are usely not well seen and we will not discuss them.
An important mediastinal-lung interface to look for is the azygoesophageal line or recess (arrow). #Clinical #Anatomy #Radiology #CXR #Normal #Labeled #Azygoesophageal #ParatrachealStripe #RadiologyAssistant #ParaAorticLine #PAView #RadiologyAssistant