sorry i think god wanted me to ask one last question i was just reading yr replies and saw u didnt indicate ct without contrast but only ct . did u mean ct without contrast . just to concluse  what u said  if a tumour compresses immunity  , in that case the tumour will be big enough and create symtoms which u indicated and will be easily picked up by ct scan without contrast.by ct scan.  and if the tumours are minute and cant be picked by ct scan withoiut contrast  then they cannot compress immunity being so minute  and so antibodies will be there and it will not create  false negative test.   for anxiety sake just formulating ur reply so as not to  disturb u again thanks  waiting sir