Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Compared with ___ at 09 : 14 , the degree of consolidation / retrocardiac opacity at the left lung base has improved . There is some residual retrocardiac opacity as well as a residual small left effusion . Mild upper zone redistribution , but no overt CHF . Aside from minimal basilar atelectasis , the right lung is grossly clear . No right effusion . Cardiomediastinal silhouette is grossly unchanged . Right IJ the seen lead overlies the right ventricle , as before . On the current study , the tracheal air column is not well visualized between the clavicles and aortic knob . It is well seen on the most recent prior study .
    OUTPUT:
    
1 . Partial interval clearing of retrocardiac density . No new focal infiltrate identified . 2 . Poor visualization of a portion of the tracheal air column . Question artifact . Clinical correlation requested .