Lung Collapse

By Dr Deepu


The cardinal radiographic features of lobar collapse are
1. increased opacity of the affected lobe-A collapsed lobe appears radiographically dense due to a combination of retained secretions or fluid within the lobe and reduction in aeration of the lobe
2.volume loss - can be inferred by direct and indirect signs.
A.Direct signs of volume loss refer to displacement of interlobar fissures, crowding of  pulmonary vessels and bronchi.  Hilar elevation on the PA chest radiograph is a well-known sign of upper lobe collapse:
B. indirect signs include compensatory shifts of adjacent structures such as hyperinflation of other lobes and mediastinal shift (trachea etc)
  The normal lung parenchyma should expand proportionally to compensate for the degree of collapse and often the greater the degree of lobar collapse, the greater the compensatory overinflation.
Therefore when small lung volumes are involved, the hyperinflation usually only involves the remainder of the ipsilateral lung, whereas with larger volumes, the contralateral lung may expand across the midline.
Shifting granuloma sign ----Hyperexpansion may also result in a change in position of lung lesions, such as granulomas resulting in the so-called shifting granuloma sign
The Luftsichel sign (from German, meaning air crescent)is a particular manifestation of the hyperexpansion. It is due to the overinflated superior segment of the ipsilateral lower lobe occupying the space between the mediastinum and the medial aspect of the collapsed upper lobe, resulting in a paramediastinal translucency . The sign is more common on the left than the right and is regarded as a typical appearance of left upper lobe collapse

Juxtaphrenic peak of the diaphragm ---- A useful ancillary sign of upper lobe collapse (or a combination of right upper and middle lobe collapse) is a juxtaphrenic peak of the diaphragm . The sign refers to a small triangular density at the highest point of the dome of the hemidiaphragm, due to the anterior volume loss of the affected upper lobe resulting in traction and reorientation of an inferior accessory fissure

Golden's S sign ---The sign refers to the S shape (or more accurately, reverse S on the right) of the fissure due to the combination of collapse and mass centrally resulting in a focal convexity with a concave outline peripherally.Lobar collapse due to a central obstructing bronchogenic carcinoma is most likely when Golden's S sign is seen.