Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Low lung volumes are present . The heart size is unchanged appearing borderline enlarged . Mediastinal and hilar contours are similar . There is crowding of the bronchovascular structures without overt pulmonary edema . A patchy opacity is demonstrated in the left lower lobe , potentially due to atelectasis though infection can not be completely excluded . No pleural effusion or pneumothorax is visualized . There are no acute osseous abnormalities .
    OUTPUT:
    
Low lung volumes with patchy left lower lobe opacity , potentially atelectasis , but infection is not completely excluded .