Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Low lung volumes are present . New moderate - to - large left pleural effusion is noted which obscures the cardiac silhouette thereby making assessment of the heart size difficult . Additionally , there is left basilar opacification which may reflect compressive atelectasis though infection or aspiration can not be completely excluded . There is likely mild pulmonary vascular engorgement . No pneumothorax or right - sided pleural effusion is identified . There are no acute osseous abnormalities .
    OUTPUT:
    
Moderate - to - large left pleural effusion with left basilar opacification likely reflecting compressive atelectasis though infection or aspiration can not be excluded . Mild pulmonary vascular congestion .