Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiomediastinal silhouette and hilar contours are unremarkable . The heart size and mediastinal width is exaggerated by AP technique and is not significantly changed to prior exam . There is some mild left base atelectasis . The lungs are otherwise clear . There is no pleural effusion or pneumothorax . There is no subdiaphragmatic lucency to suggest pneumoperitoneum .
    OUTPUT:
    
No acute intrathoracic process . No evidence of pneumoperitoneum .