Learning Radiology xray montage

Atelectasis of the Left Lower Lobe

General Considerations

  • All types of atelectasis involve loss of volume in some or
    all of a lung with resultant increased density of the involved lung
  • The atelectasis referred to here is that caused by bronchial obstruction, usually a tumor (i.e. a bronchogenic carcinoma), a foreign body or a mucus plug 

Signs of atelectasis 

Lower Lobe Atelectasis

  • Lower lobe is usually tethered to the hemidiaphragm and mediastinum by the inferior pulmonary ligament (IPL)
    • The IPL attaches the lower lobe to the mediastinum
      and may be seen normally on CT scans of the chest
    • The inferior pulmonary ligament is actually not a
      ligament but reflections of the pleura (visceral and parietal) inferior to the hilum extending downward to the
      diaphragmatic pleura
      • It is on the medial border of the left lower lobe
      • There is no superior pulmonary ligament as a
    • With collapse, there is rotation of the major fissure
      posteriorly and medially

Imaging signs of Left Lower Lobe Atelectasis


  • Following cardiac surgery, especially in which there is topical hypothermia of the heart and phrenic nerve

Left lower lobe atelectasis

Left lower lobe atelectasis. The blue arrows point to the edge of a triangular region of increased density
in the left cardiophrenic sulcus representing the major fissure with the atelectatic left lower
lobe medial to it. The red arrows on the axial CT of another patient show the atelectatic left lower
lobe bounded by the displaced major fissure.
For this same photo without arrows, click here

Left lower lobe atelectasis

Left lower lobe atelectasis. The frontal view demonstrates a sharp edge which is the major fissure and a triangular density at the left base behind the heart (white arrow). On the lateral view, the area of increased density is seen posteriorly (red arrow) while only the right hemidiaphragm is visualized since the left is being silhouetted by the atelectasis.

For additional information about this disease, click on this icon if seen above.

British Journal of Radiology 74 (2001),89-97 © 2001 Lobar atelectasis: diagnostic pitfalls on chest radiography K Ashizawa, MD, K Hayashi, MD, N Aso, MD and K Minami, MD 

Radiology, Vol 148, 479-483, Copyright © 1983 by Radiological Society of North America   Inferior pulmonary ligament: computed tomographic appearance   RC Rost Jr and AV Proto