Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size remains moderately enlarged , similar compared to the previous exam . The mediastinal and hilar contours are stable , and there is no pulmonary vascular congestion . Mild elevation of the left hemidiaphragm is unchanged , and a patchy opacity in the left lower lobe appears similar compared to the prior exam . A small left pleural effusion may be present . No pneumothorax is identified . There are multilevel degenerative changes in the thoracic spine .
    OUTPUT:
    
Patchy opacity in the left lower lobe , similar compared to the prior study , and could reflect an area of atelectasis . A small left pleural effusion may be present .