Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Compared to ___ , patchy opacity at the left base has increased slightly , with slight interval obscuration of the diaphragm . While this could represent progressive atelectasis , the differential diagnosis could include an early infiltrate or area of aspiration . Minimal blunting of the left costophrenic angle is also seen , though this is not significantly changed . There is also slight patchy opacity at the right cardiophrenic region and minimal blunting of the right costophrenic angle , which are similar to the prior film . There is upper zone redistribution , which may be accentuated by low inspiratory volumes . The cardiomediastinal silhouette is unchanged . No focal infiltrate seen in the upper or mid zones in either lung .
    OUTPUT:
    
Bibasilar atelectasis . Changes at the left base are slightly more pronounced than on ___ . The possibility of an early infiltrate or area of aspiration is in the differential . Upper zone redistribution , without overt CHF . This is likely accentuated by low inspiratory volumes .