Atelectasis | Chest Radiology Essentials

Atelectasis is a condition in which the lung or a part of it collapses and does not expand properly during breathing. There are several forms of atelectasis, each with its own set of causes:
1. Passive (a.k.a Relaxation) Atelectasis: This form of atelectasis happens when something in the pleural space, such as fluid or air, permits the visceral pleura to freely move and allow unimpeded elastic recoil of underlying lung parenchyma.
2. Adhesive atelectasis: This occurs when there is a lack of normally functioning surfactant, which is a substance that helps the lung expand during breathing. Without enough surfactant, the alveolar spaces stick together, making it difficult to expand.
3. Obstructive (a.k.a. Resorptive) Atelectasis: This type of atelectasis occurs when there is a central airway obstruction that prevents air from reaching a part of the lung. This may be caused by mucus plugs, tumors, foreign bodies, or narrowing of the airway.
4. Cicatricial (a.k.a. Contraction) atelectasis: This type of atelectasis occurs when scarring/fibrosis prevents lung from expanding properly. This may be due to scarring from lung disease, such as pulmonary fibrosis, or from surgery or radiation therapy… or from pleural disease.
Round atelectasis: This uncommon form of cicatricial atelectasis occurs when pleural fibrosis prevents a region of peripheral lung from expanding.
The treatment of atelectasis may involve addressing the underlying cause. Causes of atelectasis can vary depending on the type, but some factors include surgery, trauma, prolonged bed rest, chronic disease, malignancy, and certain medications.
Some of the case images in this talk appear courtesy of Ahmed El-Sherief, MD.
Chapters:
00:00 - Introduction
05:58 - Passive Atelectasis
11:25 - Adhesive Atelectasis
18:36 - Obstructive Atelectasis
25:35 - Obstructive Atelectasis: Right Upper Lobe
29:12 - Obstructive Atelectasis: Right Middle Lobe
32:06 - Obstructive Atelectasis: Right Lower Lobe
34:05 - Obstructive Atelectasis: Left Upper Lobe
35:52 - Obstructive Atelectasis: Left Lower Lobe
38:13 - Cicatricial Atelectasis
40:18 - Round Atelectasis
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[@amamaelnaby]

I really like how you simplify the concepts with diagrams 👍

[@tao072002]

Great analogies in this talk!

[@ilikokherodinashvili2499]

thanks for the information

[@romsa]

Thank you very much! Could you please tell me if the term "infiltration" is used when describing CT scans?

[@radiologyframeworks]

"Infiltration" is a term that's not commonly encountered with respect to the CT scans. If folks do use this term, it's typically on chest x-rays when they see a nonspecific lung opacity. Since CT imaging usually affords us the capability to be more specific in characterizing a lung opacity, the need to use a "catch-all" nonspecific term like "infiltration" is much less.
Many subspecialist chest radiologists - myself included - discourage the use of the term "infiltration" altogether - not be cause it's nonspecific, but because it means different things to different people and is therefore ambiguous in its meaning. For some folks, an "infiltration" could represent atelectasis, infection, non-infectious inflammation, hemorrhage, neoplasm, or interstitial fibrosis in the lung, while for other folks it might represent a subset of these items, and for some it might just mean "probably pneumonia".
Since we strive to avoid miscommunication that may affect clinical management, a term like "opacity" is favored since it tends to have a more consistent interpretation by all parties.

[@Deadioan196]

Hello nice talk, I have 1 question: what do you think about distinguishing atelectasis versus consolidation(alveolar filing) by the degree of enhancement on CT with contrast?

[@Deadioan196]

Thanks

[@radiologyframeworks]

A useful feature, as atelectasis enhances avidly and consolidation less so, and often heterogeneously!