Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The mediastinal and hilar contours are normal . The pulmonary vasculature is normal . A small left pleural effusion appears similar in size compared to the previous chest radiograph . Associated patchy left lower lobe opacity could reflect compressive atelectasis , though infection is difficult to exclude . Minimal atelectasis is noted in the right lung base . No pneumothorax is identified . No acute osseous abnormalities detected .
    OUTPUT:
    
Unchanged small left pleural effusion . Patchy left lower lobe opacity may reflect compressive atelectasis , however infection is difficult to exclude . Minimal right basilar atelectasis .