Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There are relatively low lung volumes . Right base opacity may represent combination of atelectasis with underlying consolidation , particularly medially . Somewhat rounded retrocardiac opacity with subtle lucency is consistent with patient 's known hiatal hernia . Adjacent atelectasis may be present . There is slight blunting of the left costophrenic angle and a small pleural effusion is not excluded . The cardiac silhouette is top normal . The aorta is calcified . There is no pneumothorax . There is no evidence of free air beneath the diaphragms .
    OUTPUT:
    
1 . No evidence of free air beneath the diaphragms . 2 . Bibasilar opacities may be due to atelectasis ; however , underlying consolidation is not excluded in the appropriate clinical setting or trace left pleural effusion . 3 . Known hiatal hernia .