Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Since the prior chest radiograph , there has been improvement in the nodular heterogeneous opacities bilaterally , with still some mild residual airspace disease in the regions of prior , more distinct consolidation . The nodular opacity in the left midlung is no longer well appreciated , and was likely due to prior infection . Lungs are hyperinflated compatible with COPD . Heart size is normal . Again noted is an enlarged main pulmonary artery , which may indicate pulmonary hypertension . Calcification of the aortic knob is again noted . No pleural effusion or pneumothorax . Mild biapical scarring is redemonstrated . The lateral view demonstrates lower thoracic spine compression fractures , unchanged .
    OUTPUT:
    
1 . Improvement in bilateral airspace opacity since the prior radiograph , with a small amount of residual airspace disease . 2 . COPD 3 . Enlarged main pulmonary artery , possibly indicative of pulmonary arterial hypertension . 4 . Unchanged thoracic spine compression fractures .