Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable upright view of the chest demonstrates small right pneumothorax , significantly decreased in size from exam obtained one hour prior . The right lung demonstrates improved aeration . Ill - defined opacities in the right lung base likely represent atelectasis . Left lung is well expanded without pleural effusion or pneumothorax . Hilar and mediastinal silhouettes are unremarkable . Heart size is normal . There is no pulmonary edema .
    OUTPUT:
    
In comparison to study obtained one hour prior , there is significant interval improvement in right pneumothorax , which is now small .