Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Mild cardiomegaly is re- demonstrated . The aorta is unfolded . The mediastinal and hilar contours are unchanged . Pulmonary vasculature is not engorged . Linear opacities in the lung bases are compatible with regions of subsegmental atelectasis . No focal consolidation , pleural effusion or pneumothorax is evident . Mild degenerative changes are noted in the thoracic spine .
    OUTPUT:
    
Subsegmental bibasilar atelectasis .