Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Supine portable view of the chest or semi-upright portable view of the chest demonstrates low lung volumes . No pleural effusion . There is mild perihilar vascular congestion . Tortuous descending aorta is noted . Heart is mildly enlarged . There is no pneumothorax . Left lung base opacities likely represent atelectasis .
    OUTPUT:
    
Low lung volumes . Left lung base opacities , most likely atelectasis .