Pleural Effusion

Definition: Fluid accumulates in pleural space.

You are looking at pleural effusion on right, in the Chest x-ray.

Irrespective of the nature of fluid, radiologically they will look similar. 

Radiological criteria are:

• Homogenous density
• Density in dependent portion
  • Upright: Costophrenic angle in PA view 
  • Lateral view: Anterior and posterior portions of gutter 
  • Lateral decubitus position: Along sides 
  • Supine position: Along posteriorly, giving diffuse haziness on the side of effusion
• Silouhette of upper limit of density
  • Upper margin high in axilla in PA view
  • Upper margin high anteriorly and posteriorly in lateral view
  • This is just an illusion
• Loss of silouhette. Note lack of identifiable left diaphragm before and visible diaphragm after clearance of fluid (Silouhette sign principle).

Comprehend the following

What is pleural effusion?

What are the types of fluid that can accumulate in pleural space?

What are the mechanisms by which fluid accumulates in pleural space?

How does pleural effusion appear in CT?