Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Linear opacity in the retrocardiac area at the left lung base likely corresponds to atelectasis . No concerning focal consolidation , pleural effusion , pneumothorax , or pulmonary edema is seen . Heart and mediastinal contours are within normal limits .
    OUTPUT:
    
No radiographic evidence for acute cardiopulmonary process .