Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal lateral chest radiographs again demonstrate a left PICC terminating in the mid SVC . There is improved aeration of the left base . The cardiomediastinal silhouette remains normal . No focal consolidation , pleural effusion , or pneumothorax is identified . Scarring of the mid left lung is unchanged .
    OUTPUT:
    
Improved aeration of the left base .