Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Right - sided dialysis catheter again terminates at the lower SVC / cavoatrial junction slightly more proximal in position as compared to the prior study . . Patchy left base retrocardiac opacity this could be due to atelectasis , infection , are aspiration . No large pleural effusion is seen . There is no pneumothorax . The cardiac and mediastinal silhouettes are stable . No pulmonary edema is seen .
    OUTPUT:
    
Patchy left base opacity , new since the prior study , could be due to evolving pneumonia , atelectasis , or aspiration .