Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A chest tube again projects over the right hemithorax with trace subcutaneous emphysema along its external course . The cardiac , mediastinal and hilar contours appear stable . There is persistent patchy retrocardiac opacity with air bronchograms which has improved somewhat . There is a persistent small right apical pneumothorax . The distance between the superior margin of the lung and the outer chest wall is about 15 mm , which is slightly increased .
    OUTPUT:
    
Very small persistent pneumothorax on the right , somewhat increased . Improved aeration at the left lung base .