Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest were obtained . The heart is of normal size with normal cardiomediastinal contours . Retrocardiac opacity is new since ___ and may represent infection in the appropriate clinical setting . No pneumothorax . Right upper quadrant metallic clips are compatible with prior cholecystectomy .
    OUTPUT:
    
New retrocardiac opacity , which may represent infection in the appropriate clinical setting .