Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lucency adjacent to the aortic knob may be artifactual , however pneumomediastinum is not entirely excluded . Cardiac silhouette is normal . No pneumothorax , pleural effusion , or consolidation .
    OUTPUT:
    
Lucency adjacent to the aortic knob may be artifactual , however pneumomediastinum is not entirely excluded . Recommend repeat frontal and lateral radiographs or CT chest for further evaluation .