Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mediastinal and hilar contours are unremarkable . The pulmonary vasculature is not engorged . Patchy opacities are noted within the left lung base with associated small left pleural effusion . Minimal atelectasis is noted in the right lung base . There is no pneumothorax . Lung hyperinflation persists . No acute osseous abnormalities are demonstrated . There are mild to moderate degenerative changes seen within the thoracic spine .
    OUTPUT:
    
Small left pleural effusion and associated left basilar patchy opacity may reflect compressive atelectasis , but infection or aspiration can not be excluded in the correct clinical setting .