Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Near complete opacitication of left hemithorax is noted with residual mild aeration of the left upper lobe . Cause of collapse is not identified . There is shift of the cardiomediastinal sillouhette to the left . Right lung is clear and hyperinflated . Bones are intact .
    OUTPUT:
    
Near complete collapse of the left lung with leftward mediastinal shift . CT may be obtained to assess further for cause of lung collapse .