Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single AP view of the chest demonstrates unremarkable mediastinal , hilar , and cardiac contours . There is retrocardiac opacification with obscuration of the left hemidiaphragm and blunting of the left costophrenic angle , likely represents combination of atelectasis and layering pleural effusion , though can not exclude underlying consolidation due to pneumonia . Slightly increased patchy opacity in the right lower lung may represent atelectasis , though again can not exclude infectious process .
    OUTPUT:
    
Retrocardiac opacity , likely represents combination of atelectasis and layering pleural effusion , but exclude underlying consolidation / pneumonia . Slightly increased opacification of the right lower lung may also represent atelectasis and vascular structures , though can not exclude an infectious process .