Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP upright and lateral chest radiographs were obtained . The lungs are markedly low in volume , limiting assessment with at least mild pulmonary vascular congestion and upper zone redistribution . Given the low lung volumes assessment for edema is limited . The exam is further limited due to patient body habitus with the suggestion of a retrocardiac opacity which could reflect atelectasis . Pleural effusions would be difficult to exclude . Cardiomegaly is stable .
    OUTPUT:
    
Limited examination due to low lung volumes and poor penetration with vascular congestion and unchanged cardiomegaly . Retrocardiac opacity , poorly assessed , may reflect atelectasis .