Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP and lateral views of the chest : There is no pleural effusion or pneumothorax . Opacification left lung base likely represents atelectasis . Despite technique , the imaged heart appears enlarged . Aortic calcifications are noted . Surgical material from a prior CABG is seen .
    OUTPUT:
    
Opacification of the left lung base likely represents atelectasis , however , pneumonia should be considered in the correct clinical scenario .