Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Linear opacities within the left lung base appear unchanged compared to recent prior examination and are consistent with plate - like atelectasis or scarring . Flattened hemidiaphragms and hyperexpansion of the lungs suggest underlying obstructive pulmonary disease . No confluent consolidation is identified . There is no vascular congestion or pulmonary edema . A trace left pleural effusion is newly identified . Cardiomediastinal and hilar contours are within normal limits . A prosthetic cardiac valve is again noted . There is no pneumothorax . Median sternotomy wires appear grossly intact .
    OUTPUT:
    
1 . Unchanged left lower lobe scarring / plate - like atelectasis . 2 . New trace left pleural effusion .