@9 months ago with 3 notes
Right middle lobe atelectasis
In the AP film, the right heart border is indistinct (silhouette sign) if the lesion is in S5.
※Though S4 is also in right middle lobe, S4 dose not abut the heart . So S4 atelectasis does not make silhouette sign of right heart border.
The lateral film shows a marked decrease in the distance between the horizontal and oblique fissures.