Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable semi-upright frontal radiograph of the chest . Since the next most recent study , there has been slight improvement in bibasilar opacities . Persistent blunting of the left costophrenic sulcus likely represents small pleural effusion and atalectasis . Persistent left retrocardiac opacity may reflect atelectasis ; however , pneumonia is not excluded . There is also likely a small right pleural effusion . No other focal airspace opacity is detected . The heart is not enlarged . The aorta is calcified and somewhat tortuous .
    OUTPUT:
    
Small bilateral pleural effusions with persistent left retrocardiac opacity which may represent atelectasis ; however , infection is not excluded .