Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A right IJ central venous catheter terminates in the distal SVC , unchanged . Bilateral airspace opacities have improved , with significantly decreased right costophrenic angle opacification , possibly representing a small effusion . There is no pneumothorax . Moderate cardiomegaly is unchanged . Median sternotomy wires and prosthetic valves project in unchanged location .
    OUTPUT:
    
Interval improvement in bilateral airspace opacities , small opacity in the right costophrenic angle may represent a small right pleural effusion .