Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A left pectoral pacemaker is in place with two leads terminating in the right atrium and right ventricle . The cardiac silhouette is top normal in size but stable . The mediastinal and hilar contours are within normal limits . Mild diffuse calcification of the aortic arch is noted . The trachea is midline . The lungs are symmetrically expanded , with decreased volume from the most recent prior study . Hazy opacification at the bilateral lung bases compared to the prior study may be related to underpenetration on technique . No definite consolidation concerning for pneumonia is seen . No pleural effusion or pneumothorax is present .
    OUTPUT:
    
Hazy opacification of the lung bases may be due to underpenetration . No definite consolidation concerning for pneumonia .