Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a wedge - shaped area of heterogeneous opacity at the left lung base that may be caused by an acute aspiration event , . There is no pleural effusion , pneumothorax , or pulmonary edema . The cardiomediastinal silhouette is within normal limits . Incidental note is made of an old posterior right third rib fracture .
    OUTPUT:
    
Wedge - shaped opacity in the left lung base may be due to an acute aspiration event but is not specific for this process . Short term radiographic followup is recommended .