Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The mediastinal and hilar contours are unremarkable . The pulmonary vasculature is normal . Linear opacity within the left lung base likely reflects atelectasis . There is no focal consolidation , pleural effusion or pneumothorax identified . No subdiaphragmatic free air is noted . Radio - opaque 2 - cm rounded density is seen projecting in the region of the stomach .
    OUTPUT:
    
Left basilar atelectasis . No subdiaphragmatic free air .