tests

PinkGirl · 10-17-2007, 02:21 PM

How do the docs decide on CT scan, MRI, or PET scan? Does it depend on the type of cancer, or which body part it's in? I know people who have had CT scans and MRI's, but I don't know anyone who has had a PET scan. Is it
for something altogether different?

Andrea Barnett Budin · 10-17-2007, 03:57 PM

Hi Pink!

Good question. Here's my experience. I have never had a PET. My oncs said it wasn't necessary for me. I have CT scans (chest/abd/pelv) w and w/o contrast. Began ev 8 wks. After a yr, moved to ev 3 mnths. Begged for ev 4 mnths (as I get diarrhea for 3 days after scans from the drink), and they reluctantly agreed. Now I have been graduated to ev 6 mnths! Wow! This is all AFTER MET. After initial dx I was told to do nothing. I wasn't comfortable w/that, but that was the standard protocol as of '95. Maybe still...

Am going for a brain MRI tmrrw. Any prayers are welcome... I'm scheduled at 8:50AM (EST) if you happen to have a free moment. I am feeling good that my brain is normal. Well, normalish... I don't believe I have ever been *normal*. Brain -- different body part. W and w/o contrast. Last yr insur co wouldn't approve with. Said IF they see something suspicious then they will cover my having ANOTHER MRI *WITH* contrast. Report came back, no evidence of met disease, BUT it is very difficult to see anything without contrast. Don't you just love that? My onc said to just let it go... This yr -- approved. Diff day, diff numbskull on the other end. Sorry. Don't mean to be disrespectful. Some are intelligent after all. But they are clerks of a sort, not medical professionals making decisions for me. Making $$$$$ financial decisions to save as much $$$$$ as possible. That's their business. Not a good system.

Have had bone scan. Would rather have MRI of breast vs mammog (even digital). Would rather have sono w/mammog but they only do that if they find something suspicious most places I know.

When Paul was collapsing and passing out this past summer they did CT brain scan first (less $$$). Then, unsatisfied, did brain MRI, for more definitive answers.

My understanding of a PET is that it is more definitive. Hope this is helpful to your question...

Andi

PinkGirl · 10-17-2007, 07:45 PM

Is a PET scan better than an MRI? Is it a more detailed scan or is it for something different than an MRI is for?

chrisy · 10-17-2007, 08:26 PM

Hi Pink

They all measure different things. And it's a heckuva alphabet soup.

CT is more like an xray, and can show areas of different density than the surrounding tissue. So a tumor or scar tissue or necrotic (dead tumor) would appear different than the surrounding area and "show up" on a CT scan.
PET measures metabolic activity - specifically the uptake of a radioactive glucose (sugar) contrast. Since cancer cells are "sugar feeders", they will light up on a PT scan because they are actively sucking up the contrast. PT also can give false positives because inflammation or tissue repair (like after an injury or working out) will also have a lot of metabolic activity.
MRI measures the reflection of magnetic pulses. Again, different types of tissue reflects the pulse differently.

Real world example of how these come into play, from my experience:
I had liver tumor identified on CT scan. During the course of chemo, I was monitored with CT scans which showed some reduction, but may also have been dead/dying tumor. Eventually the CT scan was completely clear, NED. Oops, not completely clear! There were/are 2 tiny spots which were there all along and still are, they are thought NOT to be cancer.

Fast forward 2 years, CT scan shows new areas of concern in liver and spine. But it is not clear that either of these are cancer. So more tests - bone scan which I didn't mention but is sort of like a PT for bones. Showed no cancer there. PT scan showed that the areas of interest in the liver (this is what they called them!) did have increased glucose uptake, so they were determined to be cancer. I now get full body PT scans which thank God show stable liver lesions and ALSO show a ton of activity in my brain. BUT WAIT! Your brain cells are also sugar feeders! So that is ok! If I want to check out my brain some more, I need to get an MRI. A CT scan can sometimes show something, but MRI is best for the brain

Like I said, quite the alphabet soup - not to mention radioactive merry go round. They should choose which type of test based on what info they need. Sometimes, as Andi mentioned, they will go with a cheaper (but less conclusive) test in hopes they can rule out problems, which they sometimes can, but if something shows up, they need to follow up with the more precise test.

Hope this helps. Also hope you never need any of them! They're really fun, but you probably have better things to do with your time!

Bev · 10-17-2007, 08:38 PM

Hi Pink,

I also think docs have different philosophies. Mine has a don't test until symptoms present. I guess I'm OK with that for now.

Good luck on tests Andi. BB

Andrea Barnett Budin · 10-17-2007, 09:09 PM

THANKS BEV for your good wishes.

KUDOS TO CHRISY! PRECISE AND WELL EXPLAINED WITHOUT ALL THE MUMBO JUMBO. INTELLIGIBLE. KEEN. And thanks to you for that. I knew it. It was just rattling around in my brain as a bunch of errant words. You put them together so cohesively. I have copied them for further reflection and better absorption.

Andi

Alice · 10-17-2007, 11:32 PM

I think a Pet scan can cover a broader area. I had a pet scan when first diagnosed to see if there were any other areas in question. I think if the pet scan showed anything other than what we already knew, my onc would have ordered more tests to varify the findings. Now, if I have a concern my onc usually orders an X-ray or CT because we are looking at a particular area in question and not trying to get a picture of the whole body. My onc is also of the opinion that scans should be done if there is an area that is symptomatic. I was in a study at the time of my treatment that used MRI's mostly and I am not sure what the significance of that was. I personally think I would go "bonkers" if I had routine scans!

Alice

madubois63 · 10-18-2007, 06:28 AM

I've had routine scans for 3 years straight and was bonkers long before that started. My brain MRI is done once a year as is the bone. I am allergic to the CAT scan contrast dye, so I have to get pre-medicated (prednisone, tagamet and benydryl) before every scan. The PET and CAT are done every three months. I also get a MUGA (aka gated pool - for the heart) and a bone density scan. I am not on any treatments besides anti-hormonal (Femara) and anti-rejection meds (for the bone marrow transplant), so I haven't had a MUGA since the transplant. I believe every doctor and every situation is different. In my case, the scans every three months were started to monitor the response to chemo. Then the leukemia came along and the rules changed. I had to prove my NEDship from BC in order to get the treatment for leukemia, so the scans had to continue (and new tests added). Then they were looking for different things. My bc onc gave me the last set of scans off, but it is time again. Making appointments today - ugh!

Brenda_D · 10-18-2007, 07:00 AM

My first scan after dx was a pet/ct. They were looking for spread and used it for initial staging. It does show false positives, but I would rather "see" something and follow up on it, than miss something.
The next scan was a bone scan after chemo, to check areas that lit up on the pet/ct. Bone scan showed NED to bones, but can't check soft tissue.
I had a MUGA during A/C chemo, to measure heart function.
I recently had a chest ct to look for blood clots and problems with my port. I also had a dopplar to look for clots. Nothing was found.
I just had another pet/ct to see if the positive IM node was no longer active, and checking bones and soft tissue again.
I asked about an MRI of the chest area after chemo, but my Onc said it doesn't work in the heart area because of the movement.
I have not yet had a brain MRI, but will probably ask for that later on.