Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Postoperative changes are again seen in the left hemithorax following left upper lobectomy with volume loss and leftward shift of mediastinal structures . Surgical clips project over the left lung base , and linear scarring is noted within the left base . Small left pleural effusion is chronic . Right lung is clear . The cardiac and mediastinal contours are otherwise unchanged with atherosclerotic calcifications noted at the aortic knob . There is no pneumothorax or pulmonary edema . The left sixth rib has been partially resected posteriorly .
    OUTPUT:
    
Postoperative changes in the left hemithorax without acute cardiopulmonary abnormality .