Right lower lobe collapse has distinctive features, and is usually relatively easily identified. The absence of overlying cardiomediastinal outline makes it easier to appreciate than left lower lobe collapse.
For a general discussion please refer to the article on lobar collapse.
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Complete collapse of the right lower lobe, although usually easily seen when looked for can be missed if there is very little consolidation and film is rotated. Features include 1-3:
- increased opacity (triangular in shape) at the medial base of the right lung
- usually the medial aspect of the dome of right hemidiaphragm is lost.
- the right hilum is depressed
- descending right lower lobe pulmonary artery is not visualised,
It is important to note that the right heart border, which is contacted by the right middle lobe remains well seen.
Non-specific signs indicating right sided atelectasis may also be present (although due to the small size of the right middle lobe they may well be subtle). They include:
- elevation of the hemidiaphragm
- crowding of the right sided ribs
- shift of the mediastinum to the right
On lateral projection the right hemidiaphragmatic outline is lost posteriorly and the lower thoracic vertebrae appear denser than normal (they are usually more radiolucent than the upper vertebrae) 3.
The characteristic shape associated with volume loss usually does not allow for any significant differential diagnosis. As always one should consider:
- consolidation (of the medial basal segment of the right lower lobe)
- a pulmonary or posterior mediastinal mass
The location is also a favourite for pulmonary sequestration.
- 1. Clarke C, Dux A. Chest X-Rays for Medical Students. Wiley. (2011) ISBN:0470656190. Read it at Google Books - Find it at Amazon
- 2. Webb WR, Higgins CB. Thoracic Imaging, Pulmonary and Cardiovascular Radiology. Lippincott Williams & Wilkins. (2010) ISBN:1605479764. Read it at Google Books - Find it at Amazon
- 3. Coche EE, Ghaye B, Mey JD. Comparative Interpretation of CT and Standard Radiography of the Chest. Springer Verlag. (2010) ISBN:3540799419. Read it at Google Books - Find it at Amazon