[Sherryg683]

CAT scans will show an adnormal area, such as tumors, it can also show things that are not cancerous tumors, it does not distinguish between the two. Just shows something is there. PET scans uses the sugar dye contrast on the assumption that cancerous cells will absorb this sugar faster than normal cells and they will "light" up on the PET scan. Cons with just a PET scan alone is that there are many false positives, one study said up to around 48 percent. Usually these scans are used together. They lay the PET on top of the CAT scan and if an area that lights up on the PET, also shows a tumor area on the CAT then they are more likely to consider it indeed cancerous. A biopsy is usually need to determine cancer for sure...sherryg