Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP upright chest radiograph obtained . There is linear opacity in the lower lungs , which is most compatible with subsegmental atelectasis , though a component of aspiration or pneumonia would be difficult to exclude in the correct clinical setting . No large effusion or pneumothorax . Cardiomediastinal silhouette appears stable with coronary stent noted along the left heart border . The bony structures are intact .
    OUTPUT:
    
Lower lung linear opacity most compatible with atelectasis , though a small component of aspiration or pneumonia would be difficult to exclude in the correct clinical setting .