Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: 2 views were obtained of the chest . Low lung volumes limits evaluation with bronchovascular crowding partially obscuring evaluation of the lung bases . Retrocardiac opacity more apparent on the lateral could reflect atelectasis or developing left lower lobe pneumonia in the correct clinical setting . Cardiomediastinal sillouhette is stable and normal though aortic calcification is noted . There is no pneumothorax .
    OUTPUT:
    
Left lower lobe opacity , atelectasis vs .pneumonia .