Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are slightly low . Bibasilar heterogeneous opacities are likely minimal atelectasis . The lungs are otherwise clear . There are no pleural abnormalities . The cardiac and mediastinal contours are normal aside from unchanged mild tortuosity of the descending thoracic aorta . Multilevel degenerative changes of the thoracic spine are again seen . No rib fractures are identified .
    OUTPUT:
    
1 . Mild bibasilar atelectasis , less likely pneumonia . Otherwise , no acute cardiac or pulmonary process . 2 . No evidence of a rib fracture . Imaging evaluation of the chest cage would require detail views of locations of point tenderness .