Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mediastinal and hilar contours are unremarkable . Lung volumes are low . Patchy opacities in the lung bases likely reflect atelectasis . The pulmonary vasculature is normal . Obscuration of right costophrenic angle could reflect trace pleural fluid or pleural thickening . No pneumothorax is identified . There are multilevel degenerative changes in the thoracic spine .
    OUTPUT:
    
Low lung volumes with patchy bibasilar opacities likely reflecting atelectasis . Trace right pleural effusion versus pleural thickening . No evidence of pulmonary edema .