Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are hypoinflated with crowding of vasculature . Retrocardiac opacity only seen on frontal projection is most consistent with atelectasis . No pleural effusion or pneumothorax . Mild cardiomegaly is likely accentuated due to low lung volumes . Mediastinal contour and hila are unremarkable .
    OUTPUT:
    
Hypoinflated lungs with left lower lobe atelectasis . No pneumonia .