Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral chest radiographs demonstrate improved lung volumes relative to prior examination . An enteric tube descends the thorax in an uncomplicated course , its tip not well visualized though appears to course below the level of the hemidiaphragm . A right PICC terminates at or just below the superior vena cava . Cardiomediastinal and hilar borders are within normal limits . A retrocardiac opacity is new relative to prior examination for which infection is difficult to exclude . Bibasilar atelectasis is most pronounced within the left lower lobe . There is a small pleural effusion . There is no pneumothorax or evidence of pulmonary edema .
    OUTPUT:
    
New retrocardiac opacity for which infection can not be excluded . A small left pleural effusion is associated with atelectasis .