Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Mild enlargement of the cardiac silhouette is present . The aorta is mildly tortuous with vascular calcifications noted at the aortic knob . Hilar contours are normal . Pulmonary vascularity is not engorged . Patchy opacity in the left lung base may reflect atelectasis . Subsegmental atelectasis is noted in the right lung base . There may be a trace left pleural effusion . No pneumothorax is present . No acute osseous abnormality is detected .
    OUTPUT:
    
Patchy left basilar opacity may reflect atelectasis though infection can not be completely excluded . Possible trace left pleural effusion .