Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is top normal . The aorta remains tortuous but unchanged . The mediastinal and hilar contours are otherwise unremarkable . There is no pulmonary edema . Minimal patchy opacities in the left lung base may reflect atelectasis though infection or aspiration can not be completely excluded . No pleural effusion or pneumothorax is seen . There are mild degenerative changes in the thoracic spine .
    OUTPUT:
    
Minimal patchy opacity left lung base is nonspecific , and may reflect an area of atelectasis . Infection or aspiration however can not be completely excluded .