Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Subtle opacity seen in the retrocardiac region . There is mild pulmonary vascular congestion . The heart size is normal . The hilar and mediastinal contours are normal . There is no pleural effusion or pneumothorax . The visualized osseous structures are unremarkable .
    OUTPUT:
    
Mild pulmonary vascular congestion . Subtle opacity in the retrocardiac region , could be secondary to pneumonia in the appropriate clinical setting .