Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac silhouette remains mildly enlarged . The mediastinal and hilar contours are within normal limits . Previously noted opacity within the right upper lobe has somewhat improved with residual linear opacities likely reflecting subsegmental atelectasis . Additionally , aeration of the left lung base is improved and subsegmental atelectasis in the left lower lobe is noted . No pleural effusion or pneumothorax is identified . Inferior vena cava filter is partially imaged .
    OUTPUT:
    
Interval improvement in aeration of the right upper lobe and left lung base . Minimal residual subsegmental atelectasis is noted in these regions . No hemodialysis catheter is identified .