Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The mediastinal and hilar contours are unchanged . The pulmonary vasculature is not engorged . 7 mm nodular opacity projecting over the left lung base was not clearly seen on the prior examination . Apart from atelectasis in the lung bases , the lungs are clear without focal consolidation . No pleural effusion or pneumothorax is present . There are mild degenerative changes noted in the thoracic spine .
    OUTPUT:
    
1 . Mild atelectasis of the lung bases without focal consolidation . 2 . 7 mm nodular opacity projecting over the left lung base is new in the interval , and could reflect a pulmonary nodule . Consider nonemergent chest CT for further assessment .