Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Subtle left base retrocardiac opacity most likely represents combination of overlap of vascular structures and atelectasis , less likely consolidation . No definite focal consolidation seen elsewhere . No large pleural effusion is seen although there is a possible trace left pleural effusion . Cardiac silhouette remains mild to moderately enlarged . Mediastinal contours are stable . No overt pulmonary edema is seen . Subtle appearance of evolving H - shaped vertebra , finding in sickle cell patients .
    OUTPUT:
    
Subtle left base retrocardiac opacity most likely represents combination of overlap of vascular structures and atelectasis , less likely consolidation . No large pleural effusion , possible trace left pleural effusion , similar to prior . Persistent cardiomegaly .