Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is top normal , overall stable compared to the prior exam . The hilar and mediastinal contours are stable . There is mild blunting of the costophrenic angles bilaterally . The aorta is mildly tortuous and calcified . There is increased opacification at the left lung base compared to the prior exam . There is no evidence of pneumothorax .
    OUTPUT:
    
Mild left lung base opacification , likely secondary to atelectasis ; however , an acute focal infectious process can not be excluded . Findings were discussed with Dr . ___ by Dr . ___ by telephone on the day of the exam at 5 :___pm .