Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: 2 focal nodular left upper lobe opacities are again demonstrated and have been present radiographically since at least ___ . Is difficult to assess for subtle change over time due to positional and projectional differences between these exams , but there has not been a dramatic interval change during the long time interval . Heart size , mediastinal and hilar contours are normal . There is no pleural effusion or acute skeletal findings .
    OUTPUT:
    
2 left upper lobe nodular opacities have been present radiographically since ___ and are probably stable since that time . Positional and projectional differences limit assessment for subtle change . With this in mind , a 6 month followup CT may be helpful to confirm stability and to exclude an active process .