Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a suboptimal inspiratory effort , and low lung volumes . Allowing for changes due to this , the cardiomediastinal silhouettes are stable and within normal limits . The bilateral hila are unremarkable . Although possibly secondary to crowding of bronchovascular structures in the setting of a suboptimal inspiratory effort , there is suggestion of retrocardiac opacification , possibly representing atelectasis versus infection in the correct clinical setting . There is no evidence of pulmonary vascular congestion . There is no pneumothorax or pleural effusion .
    OUTPUT:
    
Low lung volumes . Retrocardiac opacity may represent atelectasis , however infection can not be excluded in the correct clinical setting .