pet vs. ct

krystiesq
krystiesq Member Posts: 240 Member
edited March 2014 in Colorectal Cancer #1
Why do some doctors order pet scan and some order ct scan?

Comments

  • Melanie781
    Melanie781 Member Posts: 33
    #2
    My husband has had both. The CT scan is a for a localized area. The PET scan is for the entire body. The first CT was right after diagnosis and it showed the colorectal cancer, so his pelvic and stomach area. He was injected with die for the CT. The PET scan was ordered to view his entire body for possible mets or cancer in other areas of his body. For the PET scan, they give you a radio-isotope (sp?) that is with glucose. The glucose (sugar) goes to any cancer cells and the isotope "lights" up the cancer. The CT scan was done once, before radiation and chemotherapy. There were 2 PET scans ordered. 1 at the begining of the chemoradiotherapies and another one before his surgery to remove the cancer. Since the surgery, he has had 1 more CT scan to check if they got it all. He is now going to start adjuvant chemotherapy and when that is done, they will order subsequent scans, periodically, over the next year or more.
  • shmurciakova
    shmurciakova Member Posts: 906 Member
    #3
    Hi Krystie,
    A PET scan is normally ordered when something shows up on a CT scan. Do you know what GIS is? If so, then it is easy to understand a PET vs. CT. A PET is like an overlay on top of the CT scan. Say a nodule shows up on CT. A PET is then done and that scan is like an additional layer that goes on top of the CT scan and as Melanie explained, if the "nodule" is cancer, it will light up. Keep in mind though that PET scans only light up lesions 1cm in size generally speaking. Anything smaller than that may or may not show glucose uptake...
    I hope that helps,
    Susan H.
  • HowardJ
    HowardJ Member Posts: 474
    #4
    CT will show if anything is abnormal such as tumors, cysts, etc. It won't show if a tumor is cancer or not. Cancer "lights up" in a PET scan. The two are sometimes, but not always, used together to identify cancer in the body.

    Howard
  • krystiesq
    krystiesq Member Posts: 240 Member
    #5
    HowardJ said:

    CT will show if anything is abnormal such as tumors, cysts, etc. It won't show if a tumor is cancer or not. Cancer "lights up" in a PET scan. The two are sometimes, but not always, used together to identify cancer in the body.

    Howard

    Thank you all for your responses. That helps a lot. Sometimes it is overwhelming to try to educate yourself about all of the MANY facets of this disease. It is certainly easier to ask all of you then look it up and fish through the multiple answers. Happy holiday weekend.

Discussion Boards