Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac silhouette size is normal . The aorta is mildly tortuous and diffusely calcified , unchanged . The pulmonary vasculature is normal . Subsegmental atelectasis is noted in the lung bases . Hilar contours are normal . No focal consolidation , pleural effusion or pneumothorax is identified . Seen on the frontal view only is a rounded 12 mm density projecting over the left second rib anteriorly , not clearly seen on the prior exams . Mild degenerative changes are noted in the thoracic spine .
    OUTPUT:
    
1 . Bibasilar subsegmental atelectasis . No evidence for aspiration . 2 . 12 mm nodular opacity projecting over the left anterior second rib , not clearly seen on the prior studies . Further assessment with nonemergent chest CT is suggested .