Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac silhouette is stably enlarged . Midline sternotomy wires are intact and well aligned . Persistent patchy and linear opacities in the lower lobes , most marked in the left retrocardiac region , also present on older radiographs dating back to ___ . Chronic blunting of left costophrenic angle favors pleural thickening over a small pleural effusion .
    OUTPUT:
    
No definite pneumonia , but a subtle infection in the lung bases may be difficult to detect in the setting of chronic areas of scarring / atelectasis . If there remains strong clinical suspicion for infection , short - term followup radiographs or CT may be considered if warranted clinically . .