Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views were reviewed and compared to the prior study . Low lung volumes limits the evaluation ; however , there is a possible retrocardiac opacification . There is no vascular congestion , or pneumothorax . The heart size is likely normal considering the low lung volumes . There are no concerning osseous or soft tissue lesions .
    OUTPUT:
    
A possible retrocardiac opacification could represent atelectasis ; however , in the appropriate clinical setting , pneumonia has to be considered .