Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Blunting of the left costophrenic angle may reflect focal atelectasis or trace pleural fluid . Left retrocardiac airspace opacity appears slightly more conspicuous compare to prior . The upper lung fields are clear bilaterally . There is no right pleural effusion , pneumothorax , or frank pulmonary edema . The heart remains mildly enlarged . The descending thoracic aorta is ectatic , and calcifications are seen at the aortic arch . Multilevel degenerative changes are noted throughout the visualized thoracic spine .
    OUTPUT:
    
Mild cardiomegaly and probable trace left pleural effusion . No overt interstitial pulmonary edema . Left retrocardiac airspace opacity may reflect atelectasis , although superimposed infection is not excluded .