Well I amit I knew little about these procedures at the time of my ordeal. I had cat scan in 96 for migraine headache's, it didn't show a tumor. So I went on my marry way just thinking I get headache's!. Later in 03 along with migraine's one morning I woke up after a severe migraine attack I had balance issues, hardly no taste issues, numb teeth on my left side, pain and fullness on my left side of my head, and numbness on my left side of my head. EMT ordered a MRI. That's when the little devil was revealed 3.8cm's. By the time I had my surgery it had grown to around 4.5. SO for me cat scan didn't work and delayed my ordeal, which could of been small enough to radiation in 96 maybe? They Told me depends on where the tumor at. I think there are two types of cat scans? one with contrast (which I think they inject you) and one without. IMO if you get cat scan you want the one with contrast??? But, I would push for MRI which IMO is the best and will remove any dought do to the sectional slicing pictures of the area in question