Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is scoliotic and rotated to his left . The lung volumes are adequate on the right , but decreased on the left . The retrocardiac opacity , seen on prior chest x-ray , has improved . This opacity could represent a consolidation from infectious causes or an opacification due to atelectasis . There is a minimal left pleural effusion . The right costophrenic angle is unremarkable . The heart size and mediastinal vasculature is less apparent , likely reflecting improved congestion .
    OUTPUT:
    
Improved left lower lobe atelectasis or pneumonia .