Types of Opacities in Lungs

There are two types of opacities in the lung. These two opacities have some differences,...

There are two types of opacities in the lung. One is an alveolar opacity, which lies in the alveoli of the lung and another is an interstitial opacity, which lies in the wall of the alveoli.

These two opacities have some differences, which will be mentioned below-

Alveolar opacities  

Interstitial opacities

These opacities usually tend to coalesce, like the alveoli coalesce to form the acinus                       

These opacities do not coalesce and appear discrete 


These opacities have a predilection for a particular region of the lung, like a lobe or segment of the lung, since they coalesce and spread in the pattern

These opacities don’t have any particular predilection to a lobe of the lung and tend to be diffusely located, and bilateral in distribution.


With treatment, they usually show a rapid response.

They do not show rapid response


Examples include consolidation, ground-glass opacities.

Examples include reticular opacities, linear opacities and reticulonodular opacities.


Note: the unilateral coalescing opacities in the right lung. These are alveolar opacities.

Case courtesy of https://radiologykey.com/alveolar-infiltrates-and-atelectasis/

Note the presence of bilateral pulmonary opacities. The opacities are reticular( net-like ) in a pattern. These are interstitial opacities.

Case courtesy of Dr. David Cuete, Radiopaedia.org. From the case rID: 27858



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