Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lung volumes are low . The heart size remains mildly enlarged . The mediastinal and hilar contours are unchanged . There is crowding of the bronchovascular structures without overt pulmonary edema noted . Left basilar opacification with obscuration of the left hemidiaphragm persists , and may reflect atelectasis though infection or aspiration can not be excluded . No pleural effusion or pneumothorax is detected . Minimal linear opacities in the right lung base also reflect subsegmental atelectasis . There are multilevel degenerative changes in the thoracic spine with anterior bridging osteophytes .
    OUTPUT:
    
Persistent left lower lobe opacity which could reflect atelectasis though aspiration or infection can not be excluded .