Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size , mediastinal and hilar contours are normal . Lungs and pleural surfaces are clear except for a focal linear area of scarring in the periphery of the left upper lobe . There is no pleural effusion or acute skeletal finding .
    OUTPUT:
    
No radiographic evidence of active or latent pulmonary tuberculosis infection .