Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest were obtained . There are relatively low lung volumes , which accentuate the bronchovascular markings . Given this , left base retrocardiac opacity most likely relates to atelectasis . No large pleural effusion or pneumothorax is seen . The cardiac silhouette is top normal to mildly enlarged . Cardiac and mediastinal silhouettes are stable .
    OUTPUT:
    
Low lung volumes without definite acute cardiopulmonary process .