Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A single portable semi-erect chest radiograph was obtained . Moderate left pleural effusion and retrocardiac opacity are similar to the exam of 9 :30 a .m . The right lung is relatively clear . Dual - chamber pacing leads project over the expected positions of the right atrium and right ventricle . A right internal jugular tunneled dialysis catheter tip is in the right atrium . Aortic arch calcifications are noted . Cardiomegally is mild .
    OUTPUT:
    
Moderate right pleural effusion . Retrocardiac opacity may represent pneumonia , atelectasis or other pulmonary process .