Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are slightly low . Heart size remains mildly enlarged . Mediastinal and hilar contours are unremarkable . No pulmonary edema is demonstrated . Minimal patchy retrocardiac opacity is nonspecific but likely reflects atelectasis . No pleural effusion or pneumothorax is identified . No acute osseous abnormalities are detected .
    OUTPUT:
    
Low lung volumes with retrocardiac atelectasis .