Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal view of the chest . A left central venous catheter ends in the mid SVC . Low lung volumes result in bronchovascular crowding . Retrocardiac opacity is likely atelectasis . No new opacity and no pneumothorax . There is probably a tiny left pleural effusion . Cardiac and mediastinal silhouettes are stable .
    OUTPUT:
    
Retrocardiac atelectasis . No definite pneumonia .