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CT or PET Scan

bdee
Posts: 305
Joined: Feb 2009

I'm kind of confused. On the internet I read the PET Scan shows cancer cells all over your body (blood, lymph nodes, etc.) But my doctor says the CT Scans show the tumors better. I've only had one PET scan in the 11 months they first found my tumor and that was with a CT Scan.

I'm confused as always,
Debbie

Sundanceh's picture
Sundanceh
Posts: 4408
Joined: Jun 2009

Debbie

The CT scans show the internal organ structure better and they can view tumors or growths better with a CT. They can watch tumors and can see if there is growth between scans and such, so this is the first good scan the doctors order.

The PET is used to see if there is any cancer metabolic activity "lighting" up any of the cells. The trace they put into you will go to cells in the body that can show some type of cancer activity. Insurance has to approve this test, which is why it is not routinely given, like a CT scan - the cost difference between the two is staggering.

Between the 2 scans, the doctors are better able to make a determination of cancer or not.

Take care and Go 'Horns :)

-Craig

mcsauder's picture
mcsauder
Posts: 68
Joined: Nov 2009

Debbie
you should talk more to your Doc. about this
All the best to you Mike

zigswife
Posts: 62
Joined: Jul 2009

Debbie-
Was your onc referring to your tumors in particular because of the mucin? That has been an issue with being able to rely on PET scans with my husband's tumors since they have a mucinous component to them. It sounds like there has to be a lot of activity for the PET scan to show activity through the mucin so there could be smaller amounts of activity that won't show through the mucin on the PET scan but the CT scan should show them "structurally".

bdee
Posts: 305
Joined: Feb 2009

Kind of scared me. He said the PET scan should show if the cancer is spreading into my lymph nodes, to the brain or into the blood stream. The CT scan can only show the tumors and size of tumors that are already established. He said with my kind of cancer there are always other cancer cells through out parts of my body and he counts on the PET scan to find them.
Well, according to what we were given the only tumors or cancer cells I have are the seven I've known about all along and a new mucinous mass right in the middle of my abdomen. This tumor wasn't there on my last CT scan, but it is already 4 cm big. He tells me there is no way I can have anymore surgery, so when he thinks it's needed, he'll start another kind of chemo.
Right now I'm on 5FU and Avastin. A pretty low dose on both, he calls a maintenance dose. Well I've only known I have cancer since February and I think it is too early to go on a maintenance dose.

Debbie in Arkansas
(There's so many Debbie's out there I thought this would clear it up who's typing)

KATE58's picture
KATE58
Posts: 300
Joined: Nov 2009

CT SCANS SHOW TUMOURS,MASSES ,SCAR TISSUE,ANYTHING YOU HAVE IN THERE.
PET SCANS CAUSE AREAS OF FAST METABOLIC ACTIVITY TO LIGHT UP.CANCER CELLS GROW FASTER THAN NORMAL CELLS ,SCAR TISSUE AND BENIGN MASSES. MY DOCS ALTERNATE CT SCANS WITH PET/CT (BOTH AT THE SAME TIME)EVERY 3 MONTHS.BY COMPARING THE MASSES OUTLINED IN THE CT ,TO WHAT 'GLOWS' ON THE PET THEY ARE BETTER ABLE TO DETERMINE WHAT IS CANCER AND WHAT IS NOT.AND THAT SAVES ON INVASIVE BIOPSIES.
CT SCANS CAN ONLY PICK UP MASSES ABOUT 2 MM IN SIZE OR LARGER.PET SCANS SHOW SMALLER 'INFLAMED' AREAS
4 CM IS PRETTY BIG ,A LITTLE MORE THAN 1 1/2 IN, I'D WANT THAT PET SCAN.(painless and comfortable procedure like a ct,takes a little longer.don't have to drink anything nasty,
I've had 8 of them)
IF YOU HAVE COLORECTAL CANCER ,AND I AM ASSUMING YOU HAVE, IT ALMOST NEVER GOES TO THE BRAIN.
GOOD LUCK AND GOD BLESS
KATE

lisa42's picture
lisa42
Posts: 3661
Joined: Jul 2008

Hi Debbie,

Craig explained it well above. For whatever reason, different doctors are different. My former onc would alternate each time which one he did- CT, then a PET the next time. The problem with that is that you weren't comparing apples to apples when you wanted to see cancerous growth or changes from one scan to the next. I changed oncs in June, and now this one just orders PET scans. It's actually a PET/CT scan, which has a slightly lower power CT which helps them line things up better to see things better in the scan.
I think if I were to get to the point where nothing was lighting up, then he might request a CT the next time to just monitor if anything is growing or changing. My onc claims that some PET scanning places are better than others & he believes he can rely on the PET/CT scan that I'm getting to show everything- it has shown things even smaller than 5 mm, so I guess it does catch a lot. Maybe some of the older machines are more limited in what they can catch.

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