Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Compared to same day examination from ___ hours earlier , there appears to be subtle increased opacities seen in the lower posterior lung fields clearly on the lateral view only without a clear frontal correlate . This may correspond to some retrocardiac densities . This is likely atelectatic in nature ; however , underlying infection can not be excluded . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
Subtle heterogeneous opacities in the lower posterior lung field seen only on the lateral view . This is likely atelectatic , however , pneumonia remains a consideration .