Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There has been interval removal of a left PICC . A single frontal radiograph of the chest was acquired . Hazy opacification of the mid-to - lower lungs is partially attributable to overlying soft tissues . Retrocardiac dense opacification is not significantly changed compared to the prior study and is likely attributable to atelectasis , although infection or effusion at the left lung base can not be excluded . There is no right pleural effusion . No pneumothorax is seen . The heart size is somewhat difficult to assess , although appears mildly enlarged , unchanged . The mediastinal contours are normal .
    OUTPUT:
    
Unchanged left retrocardiac opacification , likely secondary to atelectasis , although concomitant infection or effusion at the left lung base is certainly possible .