Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The film is slightly underexposed causing increased density throughout . Lung volumes are low . There is no definite focal opacity to suggest pneumonia . The heart size is top normal . Mediastinal contours are normal . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
No evidence of acute cardiopulmonary abnormality .