Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The study is limited due to patient 's large body habitus and resultant underpenetration . Low lung volumes are present . The heart size remains moderately enlarged but unchanged . The mediastinal and hilar contours are stable . There is crowding of the bronchovascular structures but no overt pulmonary edema is demonstrated . Retrocardiac opacification could reflect atelectasis though infection can not be excluded . Additionally , a small left - sided pleural effusion can not be excluded . No large pneumothorax is identified . There are no acute osseous abnormalities .
    OUTPUT:
    
Limited exam . Left basilar opacification could reflect atelectasis though infection is not excluded . Small left pleural effusion can not be excluded as well .