Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The mediastinal and hilar contours are normal . The pulmonary vasculature is normal . A left - sided pneumothorax is significantly improved from 18 :___ yesterday . A small left apical pneumothorax persists and a chest tube overlies the left hemi thorax .
    OUTPUT:
    
Small residual left apical pneumothorax , significantly improved from ___ at 18 : 15