Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are very low with vascular crowding in the perihilar regions . There is some increased density in the left retrocardiac region and the right infrahilar region , most likely atelectasis , although infection can not be excluded . The heart is top normal . The aorta is tortuous and calcified . There are intact median sternotomy wires and surgical clips projecting over the mediastinum . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
1 . Very low lung volumes limit evaluation . Left retrocardiac and right infrahilar streaky opacities may be atelectasis , although underlying infection can not be completely excluded . 2 . The heart is top normal size , but exaggerated by low lung volumes .