Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Left basilar opacity which silhouette the hemidiaphragm is compatible with previously seen loculated effusion with adjacent atelectasis / scar . There is slightly increased opacity in the retrocardiac region when compared to prior which could represent progressive atelectasis / scarring . The right lung cardiomediastinal silhouette is unchanged . Median sternotomy wires and atherosclerotic calcifications noted at the aortic arch . Compression deformity in an upper lumbar vertebral body is unchanged .
    OUTPUT:
    
Left basilar opacity compatible of the least partially loculated effusion and atelectasis / scar . Slight increased opacity at the left lower lung could represent progressive atelectasis although superimposed acute process is possible . No definite acute fracture although if high clinical concern , dedicated rib series should be considered .