CT analysis of lower lobe atelectasis due to pleural effusion

Objective:To analyze manifestation of lower lobe atelectasis due to pleural effusion on CT and study orientation of dislocated total or subtotal lobar atelectasis.Materials and Methods:Chest CT of 80 patients with pleural effusion were collected and the patients with a mediastinal mass or central bronchial lung cancer were excluded.Results:①5 patients of volume loss without focal atelectasis;②35 patients with segmental or subsegmental atelectasis;③12 patients with total or subtotal lobar atelectasis which tends to be retracted posteriorly and medially.④28 patients with total or subtotal lobar atelectasis which tends to be uplifted toward the hilus;Conclusion:Four patterns of passive lower lobe atelectasis were observed with the size of the pleural effusion.The lower lobar atelectasis tends to be retracted to the hilus mainly,rather than retracted posteriorly and medially.