Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: As seen previously , elevation of the right hemidiaphragm contour is unchanged . Heart size is normal . The mediastinal contours are unremarkable . Enlargement of the hila bilaterally is unchanged , and no pulmonary vascular congestion is identified . There is a streaky opacity within the left lung base which is concerning for an area of infection . No pleural effusion or pneumothorax is identified . There are mild degenerative changes in the thoracic spine .
    OUTPUT:
    
Patchy opacity in the left lung base concerning for infection .