Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Since the inspiratory lung volumes are greatly decreased from the prior study , increased opacification of the lower lungs is probably atelectasis . The upper lungs are clear . The pleural space is probably normal . The pulmonary vasculature is not engorged and there is no pulmonary edema . Cardiac size is exaggerated by low lung volumes . Within this limitation , cardiomediastinal silhouette is normal and unchanged from the prior study . The trachea is midline . There are no displaced rib fractures , but since the conventional chest radiograph
    OUTPUT:
    
1 . Bibasilar atelectasis . 2 . No displaced rib fracture . Since conventional chest radiographs are not a sensitive modality for the evaluation of chest cage injury . Detail views in areas of clinical concern would be more fruitful . 3 . No pneumothorax or appreciable pleural effusion .