Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear unchanged , allowing for differences in technique . There is an opacity in the left lower lung obscuring the cardiac border and left hemidiaphragm with persistent mild elevation of the left hemidiaphragm . Findings are non = specific and could be seen with atelectasis or consolidative pneumonia . Interstitial prominence in the upper zones may be due to coinciding mild congestion , but with little if any change .
    OUTPUT:
    
Retrocardiac opacity which is non-specific as to etiology . Findings suggesting mild vascular congestion associated with a persistent mild interstitial abnormality .