Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Low lung volumes are present . The cardiac , mediastinal and hilar contours are unchanged , with the heart size appearing moderately enlarged . There is no pulmonary edema . Atelectatic changes are again seen within both lung bases . There is a persistent small right pleural effusion . No pneumothorax is identified . Small hiatal hernia is better seen on the previous CT . There are mild degenerative changes in the thoracic spine .
    OUTPUT:
    
Small right pleural effusion and bibasilar atelectasis .