Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size remains mild to moderately enlarged . The mediastinal and hilar contours are unchanged . Pulmonary vasculature is normal . No focal consolidation , pleural effusion or pneumothorax is identified . Assessment of the lung apices is obscured by the patient 's chin and neck soft tissues projecting over these areas . There is minimal atelectasis at the lung bases . Degenerative changes are re - demonstrated in the thoracic spine . Small amount of free air is seen underlying the central tendon of the diaphragm .
    OUTPUT:
    
Small amount of subdiaphragmatic free air under the central tendon . No focal consolidation .