Atelectasis

Type of atelectasis

Resorptive atelectasis
Passive atelectasis
Adhesive atelectasis
Cicatization atelectasis

Roentgenogram

Direct sign
Indirect signs

Lobar atelectasis

RUL
LUL
RML
LLL
RLL
 

Resorptive atelectasis (Obstructive atelectasis)

Obstruction of bronchus from any cause: 
    • Intraluminal tumor, foreign body, secretion
    • Extralumen compression: Lymph nodes
    • Longterm change : bronchiectasis, obstructive pneumonitis
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Passive atelectasis (Compressive atelectasis)

Compression of lung by space-occupying lesion in the thorax such as pneumothorax or pleural effusion, etc.
 
Diagram
 
Mild tension Pneumothorax: there are slightly shifting of the mediastinal structure and compression of  the right lower lung field.
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Adhesive atelectasis (Relaxation atelectasis)

Abnormality of surfactant: Hyaline membrane disease, Radiation pneumonitis, Discoid atelectasis. Post radiation change shows fibroreticular infiltration distributed as portal region.
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Cicatrization atelectasis

Organing scar tissue limits expansion of lung 
 
 
Destroy lung in chronic pulmonary tbc.
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Direct sign : Displacement of interlobar fissure ( white arrow )


arrowhead = shifting of trachea to the right; Black arrow= blunting of costophrenic angle (pleural effusion)
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Indirect sign:

Displacement of hilar vessels Elevation of diaphragm ( black arrow)
Mediastinal shift Compensatory emphysema
Approximation of the ribs Tracheal shift ( arrowhead )
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Lobar Atelectasis

RUL

Elevation of minor fissure; shifting of trachea to the right; elevation of hilum; thickening of right paratracheal in complete collapse
 
 
 Golden S sign : CA lung
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RML

PA view
Lateral
  • On PA view: loss of silhouette of the right heart border(always present).
  • Lateral view: major &minor fissures approximate one another, atelectatic lobe resembles a curved, elongated wedge extending downward and forward from the hilus.
  • Apical lordotic veiw: best to demonstrate wedge shape area of atelectasis, apex point out to the lateral and the base is on the heart border.
Apical lordotic
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RLL

LLL

Triangular opacity in retrocardiac region of PA view with obliterateion of diaphragm.
Major fissure rotates backward and medialy, which upper half of fissure swings downward.
 
Lateral view shows the shifting of fissures.(black arrow=major fissure, arrowhead=diaphragm)
LLL RLL
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LUL

  • Difficult to see : Hazy density at upper lung field, may be confused with loculated pleural effusion of PA chest.
  • Anterior displacement of major fissure (yellow arrow) on lateral view.
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