I have had a lot of CT scans done throughout my 27 years and I have to say that more often than not, they have been with contrast. The reason that they use the contrast is to "highlight" more things and make them easier to see. If the CT scan is for something routine and they're not really "looking" for something, then I would have them do it without the contrast. Long term use of contrast can cause possible problems with the kidney's. Now that I am post tx, I am not supposed to have the contrast. Between the meds that I am on and the contrast if I have a CT scan often enough, I would have kidney damage in no time.