Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The right base appears clear , and the opacity seen on the prior chest radiograph was likely artifactual due to low lung volumes . Heart size is normal . The mediastinal and hilar contours are normal . The pulmonary vasculature is normal . Lungs are clear . No pleural effusion or pneumothorax is seen . There are no acute osseous abnormalities .
    OUTPUT:
    
1 . No evidence of pneumonia .